Therefore, if we must not consider the resultant behavior separate from the relationship before it, then you are making a moral[0] judgement on the validity of relationships.
Consider the following: being coerced into a relationship and consenting because you fear being fired. That is clearly coercive and wrong because the consent isn't genuine, and I don't think anyone in this thread is arguing is worth being protected. A second situation: two people with mutual attraction who end up dating (like Melinda and Bill Gates) but have a power differential. It sounds like you are saying this is a priori wrong, even if the two consent and neither party feels coerced, or that one is coerced even if they believe sincerely that they are not being coerced.
Even if you don't say it is morally wrong, you still will forbid and prohibit such relationships, adults whom aren't you and who might not have the same value judgements you have. That's why it isn't so clear cut to me and others in this thread.
[0] I say wrong and moral, because this is an argument about morality, fundamentally.
In a word, no. It implies that the class of covered activities is too risky for the company.
Consider company rules about receiving gifts from vendors. Typically, there's some limit, like $25. If you are negotiating a contract with somebody and they give you a $26 pen or even a $100 pen, is that morally wrong? No, unless that's enough for you to improperly favor them. But it's still forbidden, and the danger to the company is significant enough that they still ban it.
I think it's okay to prohibit relationships that have a high likelihood of causing problems for the company, just like it's okay to prohibit (legal, morally-permissible!) behavior that is likely to detriment the company in other ways such as all engineers having root on production boxes.
If it's probably gonna cause problems it doesn't matter if it's legal, or if it's morally permissible under certain moral frameworks: don't do that shit, and it's fine for a company to ask you not to. Having relationships with subordinates is likely gonna cause problems, because most relationships end, and many of those that end will end poorly. All it takes is one lawsuit or even some bad PR to damage the business.
There seems to be no good way to make this point, but most relationships have some power imbalance. Where do we stop? Can you only marry someone your age with similar incomes? Do we encode this into law? Does this become a caste system?
The world seems to be okay with the relationship Bill Gates has. Wouldn't the world be a better place if we wondered how to foster such successes more often instead of designing rules based on an assumption of guilt in essence? Maybe rules that would forbid Gates current marriage aren't as thoroughly thought out and wise as they might seem at first blush.
Designing rules to prevent a worst case scenario sometimes goes very bad places. I have joked it can be a little like me starting a dating profile and putting "No rapists!" at the top of it. This isn't going to accomplish anything good and is likely to go bad places. Good policies need to consider more scenarios than just that worst case scenario we absolutely don't want to see.
Tldr: Let's not throw the baby out with the bathwater.
If you decide to go date a rich man on Tinder, you can break up without significant consequence to your income or your career. But if your boss asks you out you may face severe career consequences just for saying no. If you say yes and then break it off, the risks to you go up.
This rule has no assumption of guilt. It's just acknowledging the risk to the company and the people involved.
Most companies are not behemoths. Everything I have ever read indicates most companies qualify for definitions of small to mid sized.
SMEs outnumber large companies by a wide margin and also employ many more people. For example, Australian SMEs make up 97% of all Australian businesses, produced one third of total GDP, and employ 4.7 million people. In Chile, in the commercial year 2014, 98.5% of the firms were classified as SMEs.[1] In Tunisia, the self-employed workers alone account for about 28% of the total non-farm employment and firms with fewer than 100 employees account for about 62% of total employment.[2] In developing countries, smaller (micro) and informal firms, have a larger share than in developed countries. SMEs are also said to be responsible for driving innovation and competition in many economic sectors.
https://en.wikipedia.org/wiki/Small_and_medium-sized_enterpr...
> At best you could say it might has another name on it.
...does disservice to the influence she had (on Bill & the world) and shortchanges her contribution.
Your point still stands, i.e. that the claims of harm of the policy are post-hoc reasoning and therefore irrelevant its expected utility. But that does not actually conflict with this one particular instance possibly being a lucky coincidence.
One, the fact that a rule might have downsides is not proof that it's a bad rule.
Two, if the rule had existed, it's hardly impossible that they would have gotten together later, or found some accommodation.
Three, if they hadn't gotten together, there's no reason to think they both wouldn't have gone on to find happiness with other people.
Four, your suggestion that them not dating means a Bill Gates foundation wouldn't exist is without evidence. At best you could say it might has another name on it.
Five, even if this rule would somehow have caused Gates to just burn his billions instead of doing some good, you haven't grappled at all with the harm that the lack of that rule does to many people who aren't as famous.