Making admissions and recruitment fair is not simple.
For example, state school pupils are underrepresented at Oxbridge. What should be done about that?
At one extreme, you could argue that Oxbridge should not do anything. However, we know that some state school pupils do not apply to Oxbridge because they think it is "not for the likes of us" - a view sadly perpetuated by some schools. Oxbridge may therefore be missing out on some very able pupils who don't apply. We also know that independent school pupils have some built-in advantages - smaller class sizes and being better prepared for the Oxbridge interview process. This means that an independent school pupil is more likely to be admitted than a state school pupil of similar ability. Indeed, we know that currently an independent school pupil is more likely to be admitted than a state school pupil with identical grades. So doing nothing perpetuates a system that results in independent school pupils getting places ahead of more able state school pupils.
At the other extreme, you could set targets and say that you must admit x% of state school pupils. That is just as bad in my view, and leads to state school pupils getting places ahead of more able independent school pupils.
The goal should be to find a system that is fair to both state school and independent school pupils. Part of that is changing the image so that state school pupils realise Oxbridge can be for them, but it also involves finding ways of removing or countering any bias towards independent school pupils in those making admissions decisions, and ensuring the process identifies the most able candidates regardless of background.
In the above applies whether you are looking at admissions or recruitment for paid roles, and whatever communities you want to look at (male/female, ethnic minorities and so on).
Unfortunately, there are a lot of places where DEI is done badly and recruitment/admissions is governed to a greater or lesser extent by quotas. That is not the right way to do it, but it doesn't mean we should abandon DEI completely. The goal is ensuring equality of opportunity, not enforcing equality of outcome. If equality of opportunity leads to equality of outcome, great, but it must not be forced.