Parzivus

Hexbear was around for a couple years before federation was a thing so a lot of people only ever post there.
Also, and I say this as a frequent Hexbear poster, the average Hexbear user has read zero theory and just wants somewhere lefty to shitpost. There is not a ton of overlap between them and people that use Lemmygrad/Leftypol/etc

TC69 got a cult (which is overstating it given how rarely it came up) because she left and could become whatever people wanted her to be. Evidently didn't hold up to the real thing, she already deleted her account.

Leftypol is still kicking well enough, all the spinoff chans are mostly dead as far as I'm aware