For what it’s worth, it’s the reason I’ve never felt comfortable associating myself with anything in the OSR broadly speaking, as it definitely had an undertone—to me at least, I’m not implying this is a general statement about anyone else—that it was fairly reactionary.
While I suppose it is objectively reactionary in a gaming sense—specifically to the release of 4E, it also seems to have appealed towards some who are reactionary in a broader sense. Now, whether that was intentional or not, seems irrelevant.
3E, for the record. When I first got into it 4E was new, but the scene had been around for several years. Dragonsfoot.org forum custom was to refer to 3E and 3.5 as TETSNBN (The Edition That Shall Not Be Named) and then 4E subsequently as YAETSNBN.
We know the scene first started getting talked about as a movement around
2004.
There was always a mix, though, of folks who really found WotC-era D&D distasteful/objectionable/an insult to Gary and Goodness, and folks who liked parts of it but just eventually decided they were more interested in and excited by the old school. Dan Collins of Delta's D&D Hotspot (one of the classic deep-dive OSR blogs since 2007) is a classic example of the latter. A Gen Xer who started with Holmes Basic, was a fanatical AD&Der who drifted away from D&D in the 90s, came back with 3E as a lot of folks did but eventually found it unsatisfying, and then that prompted him to dig back into the original stuff, especially OD&D. Which he found to be a revelation and to retroactively make sense of all sorts of parts of AD&D he had never quite grokked because Gary originally wrote expecting his audience for 1E to be familiar with OD&D.
The OSR started with a bunch of never-left-AD&D (or occasionally OD&D) players who converged online once WotC did away with TSR's hostile policy toward fan sites, then was reinforced with a wave of nostalgic players who had left D&D in the 80s or 90s (due to adult responsibilities or what have you) and been brought back to it with the 3E publicity but found (sooner or later) that 3E didn't scratch the itch. I think a big part of the core impetus for the Renaissance or Revival was figuring out WHY. Looking at the original texts and working out what about them made for a compelling game experience that was different from Trad play. And exercises like
Philotomy's Musings deliberately saying "Hey, maybe the stuff like doors always being stuck for PCs but not for monsters, or monsters being able to see in the dark but not anymore if the PCs charm them, from the original rules, aren't DUMB design but are actually fun and interesting design? What if we just accept them and come up with rationales for them, like the Mythic Underworld concept?"
But similar to the original 1970s division of players as mostly coming from the Wargaming hobby or the Sci-Fi Fan hobby, these different groups had somewhat different perspectives and priorities and agendas of play.
Similar to how OD&D broke out and became a surprising success and phenomenon* once those two groups were both tapped (as opposed to just the original expected audience of wargamers who also enjoyed reading sci-fi and fantasy), I am inclined to think that the OSR became a thing once the never-left-AD&Ders and the returned-and-nostalgically-questing-for-their-childhood-enchantment populations converged in sufficient numbers.
(*and then became a larger pop culture fad after the Egbert case, starting in late '79).
What started, at least in my opinion, as a movement rejecting a trend in game mechanics and an embrace of legacy systems, has, for whatever reason, also attracted some who also reject the valid criticisms of many TTRPGs as having discriminatory concepts built-in to the games.
I think this is related to the mix of different populations above. I suspect the "never left AD&D" crowd has a higher percentage of older reactionaries who don't want to examine the subtext and/or found it insulting to them and to Gary's memory (despite Gary's notorious quotes here and elsewhere), like we saw with Ernie. And here we come to the BroSR, which seems to be younger than the original 1st/2nd wave AD&D holdouts, and is kind of reiterating/repeating some of the OSR mechanics/playstyle examination ("Hey, maybe 1 to 1 timekeeping like Gary talks about in AD&D as a technique to use with large play groups is actually AWESOME and a linchpin to cool campaigns!"), while also unfortunately buying into reactionary culture war nonsense in keeping with the contemporary manosphere.