I think posts of this nature (including OP) reflect a fear of not belonging to the dominant ‘caste’ and of being seen as either losing status (dominant caste men not getting jobs they are ‘the best’ for); or, alternatively, lower caste men wanting to be seen as valuable in a space they continually feel they do not belong in.
I say this as a someone who is a minority who regularly is discriminated against - and who has easily attained markers of success. There is no way to avoid feeling like we do not belong, but returning us to poverty and shutting us out of jobs is definitely not a way to attain a feeling of belonging.
Finally, DEI initiatives are very public - nepotism, alma mater connections etc are not. Let’s be careful in assuming that the only non-LEET code metric used to hire people is the color of the skin or their biological sex.
These sorts of initiatives are trying to cure a racial or sexual bias with a different sort of racial or sexual bias. How does the question "why they exist" help those of us who think, in Kant's deontological terms, that racial or sexual biases are wrong?
Please consider an old house you may buy if you live in New England or Europe. Sure, if you were building a new house everything should be plumb and level. But the house you’re able to buy in old cities is not brand new. So what does one do if you wish to have a level floor? We add shims to obtain some objective reasonable result, accepting that to get to a this result we must try to address systemic problems that are not our fault, but are now our responsibility.
Let me offer you a different metaphor about levels :-) In Greek mythology, there was a character named Procrustes. He had an iron bed of a certain size, to which he strapped his captives, and if they happened to be taller than the bed was long, he cut off their legs to fit the bed; whereas if they were shorter, he stretched them to fit the bed tearing their sinews and muscles. That's what I think of when I hear about arbitrary levels applied to living people.
In fact, this practice only really ended in the 1960s; controversially, one might even say that this practice continues to today.
So what do we do when confronted with an anecdote from antiquity versus system inequities from our modern era?
I guess, in the spirit of the analogy, your options are to either stop cutting off body parts from anyone, or to start cutting them off those who look like people who engaged in body cutting two or more generations ago. DEI prefers the second option. Some people would rather see the first.
problems that are not our fault but are now our responsibility
That’s a very nice, concise way of summarizing the essence of the issue.
For example a white friend in South Africa has a daughter who years ago, when looking at university applications, was distraught because to study to be a doctor she had to hit over 90% in her exams, vs 70% for her black South African classmates. Does it matter to her that this wasn't meant to happen? Or is reality also worth talking about?
Please take a moment and reflect on why these sorts of initiatives exist. It was not because one day we decided to chastise the down-trodden majority class.