I will give you credit for having an explanation that at least makes more sense than "the diversity statement is just for fun and doesn't do anything", which is the explanation that I usually hear!

But yeah I am aware that the more reasonable DEI supporters say things similar to what you said. Just be aware that there are other people who are skeptical that the "improve outcomes for a variety of minority groups" part actually happens, and also think that DEI has various other negative consequences in addition to that.

I wouldn't really say I needed to "suck it up" since not winning the GRFP is a pretty minor thing - it's very hard to win, so a negative outcome was not really surprising and didn't really cost me anything more than a line on my resume. I was happy to even get honorable mention! My actual concern is when similar tactics are used for more meaningful things, and the second order effects of such policies. The GRFP was just the biggest example of it directly affecting me personally, since I didn't stick around in academia too long (for multiple reasons, not just DEI), so it makes a good enough anecdote I guess.