The words "diversity" and "inclusion" aren't new, but the current behaviour of those using them is a recent shift.
It's now a form of parasitic corruption of organisation, where people in the role create power bases to undermine the leadership, root out dissenters, and grow their departments. In the other thread you can see how they get rid of people who ask difficult questions like Peter Boghossian - the students create the complaints about wrongthinkers like him, and the DEI people then act as their enforcers.
There's no more need to believe you're going to get "diversity" or "inclusion" or "equity" out of a "Diversity Equity & Inclusion" department than you have to believe you're going to get "democracy" or a "republic" from the Democratic People's Republic of Korea, or anti-fascism from Antifa. It's not always in the name, you know...
I think the reason the main emphasis in the rhetoric is on "inclusion" is it's the main compliance tool. Saying "no" to anyone is "exclusive", so "be inclusive" is the way of forcing people to agree - you have to let (some) people do whatever they want, and you cannot have boundaries. (I believe feminists might call this "rape culture"?)
Of course, this "inclusion" is just rhetoric, and is highly selective. The "inclusive" people will exclude anyone they think is remotely bad for everyone's "safety". "No TERFs on our turf", sort of thing...
At this point I would say it's probably best for companies, universities and the like just to completely shut down any DEI department they have. I don't think they're compatible with the sort of authoritarian top-down, non-democratic structure you get in a company. They end up with more power than it's safe to give to ideologues, and are likely to get the company into legal trouble, as seen with Maya and Allison's case. They don't really care about fairness or the law, and will crush any individual getting in their way.
But it may be more possible to hold them in check in government? Maybe? I think some progress has been made reigning in Stonewall in Whitehall, for example. Something like the EHRC can work, with public transparency, I think, even though it is a form of "DEI", and you do need something. Diversity, equity and inclusion can be somewhat worthwhile general aims, when not perverted and turned into weapons.