I do not think that is the problem of 80%+ one gender groups.
Imagine going into a store and see that 80%+ is the opposite gender. Before anyone has a chance of accommodating your need, what emotions pops up? Now compared that to going into the same store with the 80%+ being your own gender.
Going into an environment where you feel like a part of a dominating group give most people a feeling of security. They feel safe and what ever choice everyone else does is a safe choice to adapt. Entering a group where you are a minority has not just the absence of that, but can also induce a sense of insecurity.
This is one theory why countries like Sweden have a very extreme gender segregation of around 90% of men and 90% of women working in a gender segregated profession. From student to senior employee, every step is impacted in how secure the person feel in continuing with their career path, and the above effect influence how leaky the pipe get.
Why “naturally”? Is it really natural for men and women to alienate each other just by existing?
Are they? I worked in the mental health space for over 10 years and almost 80% of therapists are women -- and a vast majority of those are white women. There hasn't been any significant movement to "fix" that despite a very compelling argument that finding a therapist who is a good match to a patient is fundamental to the success of treatment -- there's actually a scientific case to be made that more diversity in mental health care is beneficial to outcomes. However, there's little evidence that "more women" designing silicon chips has any measurable benefit (or harm.) Having more women (and old people, and people from different cultural backgrounds) involved in UX design is definitely valuable -- but more women writing back-end server code or designing airplane wings has little effect either good or bad.
Women vastly outnumber men in the social sciences and in education however, "We need more men kindergarten teachers" has never been a serious initiative. Getting more women into commercial fishing, oil field work, plumbing, or over-the-road trucking has never been seriously pursued. But "computer science" -- it's a damned obsession with people of certain politics.
It's a fact that men and women are different, both biologically and socially. Women can certainly be exceptional computer workers and men could be great therapists or kindergarten teachers -- but that doesn't mean they necessarily want those things nor are they necessarily pre-disposed with the characteristics necessary for success in those fields. It's a fact, for example, that there are gender differences in spatial reasoning. That doesn't mean all men are better than all women at spatial reasoning, but it does mean that men have a statistically higher success with spatial reasoning than do women as a group. Women have their own advantages over men as well. There is nothing wrong with differences and it has gotten stupid how people insist on claiming that everyone is equal. They're not. Everyone has strengths and weaknesses.
This insistence that we have to "fix" the "problem" is just woke nonsense. We should absolutely, 100% end discrimination in the professions -- no question or debate there. But we should stop trying to force equality as an outcome. Let people gravitate towards the things they're good at or care about instead of trying to social engineer everything to please some imaginary ideal. If a girl wants to hack on compilers -- we should get out of her way (i.e. removing bias and discrimination) and let her do it. But we shouldn't be focused on going into third-grade classrooms and trying to convince girls that they should care about hacking on compilers. We should be focused on exposing every student to vast possibilities, but we don't need to force it down people's throats as a social imperative.
While all the other things you mentioned other than maybe oil field work are not as financially lucrative.
In short, the goal is to put people of a certain group in positions of power and influence.
In other words, you'd effectively be taking would-be male engineers and converting them into nurses and teachers. And vice versa. The number of people that consider those fields a toss up is vanishingly small. They require completely different skill sets.
While contrived, I'm convinced this is precisely the problem. If I am a woman on a team of men, am I a bit of a jerk for demanding that the rest of the team accommodates me? Perhaps they all have a communication style that suits them that is born from their upbringing as male children while I have a communication style that equally suits me, but is different from theirs. Must I adapt to their system, or should they adapt to mine?
When we talk about programming style, or preferences for tools the answer is seemingly easy. We go with the majority so that we please the most people. When we talk about gender, sexual orientation, race, etc the answer is much more complex. We can divide our groups in infinite ways and yet some categorisations are chosen to be significant while others are not.
Because of this, I feel that it is actually really important that we recognise that we will not and can not accommodate everyone. Being different, having a different opinion, having a different set of experiences is not actually enough to warrant special treatment. In many cases we choose to discriminate: no matter how good a Java programmer you are, we will not write our frontend in GWT! (Real story: I maintain a frontend written in Java and GWT, so I'm taking some liberties ;-) ).
As I said, there are some special cases where we have decided that we wish to provide special accommodation. We do this because, on balance, we believe that doing so enriches our societies. It will always be a tradeoff, though, and it's important to understand that.
Consider the word "discrimination". Without that word, we can not discriminate between "good" and "bad". We do not want to live in a world without discrimination. We should always strive to discriminate in such a way as it makes the world a better place. We wish to avoid behaviour that works against our interests and encourage behaviour that works for our interests.
To that end, we specifically discriminate in certain situations so that we accommodate minority groups in a way that we feel enhances our society. It should not be a surprise if we occasionally get this wrong and I strongly discourage people from assuming that the "right" answer is easy to determine. It is important that we think very carefully about which things we wish accommodate (minority representation of gender, sexual orientation, race) and things which we do not wish to accommodate (hate speech, violent behaviour, and GWT :-D).
P.S. I hereby apologise for my horrible characterisation of Java and GWT. I actually don't mind it that much...
I find your example of communication style to be trickier. It feels in-between to me. I would agree that some elements of communication style should not be changed to accommodate an inflexible newcomer. On the other hand, when people talk about the benefits of diversity, communication style is a really large element! You know what you enjoy about your current boys' club style -- but it might very well be better if you switched to something more professional even in the absence of onboarding someone new. You won't know until forced to by the introduction of diversity, and that's true in many different subtle areas, not all of which you're going to have any chance of spotting in advance.
The same argument could be applied to just about anything. Perhaps GWT would be a really great fit for what you're working on, but you won't know until you try it. That's far less likely than a communication style change, though, so it's probably one of the costlier and less likely things to try to accommodate.
I agree that the question of whether or not to accommodate a difference is not always answered with "yes!" It depends on the accommodation required.
I think its a lot more complicated than this. Yes, men and women can be jerks. The bigger issues seem to be when a team is 80%+ one gender or another, and the issues aren't about "being mean" the issues are about the dominant group being blind to and then not accommodating the nondominant group's needs.
A huge problem is that we have a lot of 6 person tech teams with 5 guys and 1 women and the women naturally feel alienated and either aren't actually able to do well or are at least perceived as not doing well due to their situation. This holds back women's career development as a group and reduces the numbers of women in higher ranks in corporate life.