They did. The entire section starting with "Of course, despite the emphasis on reason — and the subtle implication that the out-group is more wrong — the rationalist community is susceptible to the same biases as anyone else" talks about the failure of the rationalist community to be any better than any other group.
Then this describes the actual break:
> By that time, my relationship with the skeptic community was already strained; in an earlier message to the same mailing list, I said that for all the claims of being enlightened, it’s the only place where stonings are still in fashion. Even so, when I saw the Damore email, I had a brief urge to respond. I wanted to accuse him of “motivated reasoning” — a purported fallacy of constructing an argument to advance a specific conclusion, in contrast to the divine, unmotivated reasoning of real rationalists. I bit my tongue, thought to myself “wow, what a stupid game to play”, and deleted the draft.
In other words, they had been dissatisfied with the whole rationalist way of arguing for a while; and this was the point where they finally felt like "This is actually just a game of words; and it's a dumb one I don't want to play any more." The implication being that after this they no longer considered themselves a rationalist, nor engaged in its form of arguing.
ETA: FWIW, I mean... hard things are hard? It's the normal state of the world that people think they've done the hard thing but are actually just finding excuses to do what they want. People like J.D. Vance decide to be a Catholic, but turns out Jesus' actual teachings are so counter-intuitive that he still doesn't understand them and does them badly. Actually being rational is a difficult, mostly solo activity.
Quitting rationalism (or Christianity, or ...) because most of the people around you are just cosplaying is like quitting chess because most of the people around you are just playing around and never get past 1200 ELO. Or like quitting weightlifting because most people around you talk about reps and whatever but never actually push themselves enough to get past their current plateau. Like, OK, that's their problem, but what's that got to do with you?
> Like, OK, that's their problem, but what's that got to do with you?
If a social creature plays chess in a club where everyone else cosplays, the first thing that creature will do is find a better group of players to raise the challenge. Most serious chess players end up doing that sooner or later.
Rationalists are also social creatures, so that principle remains the same. To pretend that a group of cosplayers wouldn't affect a rationalist's ability to be effective is, ironically, irrational.
Also, there can become serious negative implications to terminology at the critical mass of cosplay the author implies in the article. I have neighbors who are contractors and went in on a house together. They split up time amongst their families, using it as an investment and vacation house. For very good reasons they never refer to what they are doing as "time sharing." :)
> In other words, they had been dissatisfied with the whole rationalist way of arguing for a while; and this was the point where they finally felt like "This is actually just a game of words; and it's a dumb one I don't want to play any more."
That would make sense, except for the first paragraph mentioning that the Bankman-Fried thing and the Zizian murder thing didn't prompt them to write it. Both were long _after_ the Damore thing. The strong implication of the first paragraph was that there was some _new_ breaking point, but that's quite an old one.