That's just my steelman. You are correct that it would require a readjustment at some point, i.e DEI practices can't exist forever.

"Unqualified people get promoted inspire excellence". I think at the very top, advanced work isn't done to get promotions but rather the work itself. I imagine that people don't take years of schooling and work with the goal of becoming a senior dev. There's something about the work and producing good work that motivated them.

Note that I don't work in tech but rather mathematics research. So our incentives are different, but I think the main ideas hold.