I disagree (I know you'll be surprised) because I don't think positive discrimination helps marginalised groups at all. I think it probably helps individuals within marginalised groups but at the cost of the entire group over the long term. A better way to solve the problem is to ensure your application process doesn't discriminate at all by improving the process not the outcome - a lot of that is dismantling the things like 'legacy' placements and ensuring entirely blind applications.

What you need to ensure is that people who are unsuited for a position by virtue of their talent are not put in the position because they a) know someone or b) have an irrelevant characteristic that gives them a social advantage once society has been engineered to give a rigged result. In both cases you're not treating people fairly. You cannot tackle racism with racism and you cannot tackle nepotism without removing the opportunity. You actually have to find the right people for what you're looking for, not presume who they are by social engineering or private ambition.