man why are leftist spaces online like this?
They don't start off this way. People usually start-up communities out of genuine passion, but as time goes on the only people willing to babysit/moderate the community are people who spend a lot of time on the internet already. Eventually, the whole mod team becomes people who do nothing else but chat about the community/forum. As they reinforce each other, in their minds the importance of their community/forum grows. No longer is it a fun internet site, now it's serious business, and that means that bad actors want to destroy. Then they give themselves carte blanche to "protect" the community. Naturally, with that kind of mindset anyone who disagrees with them is a potential threat, everyone who posts could be a bad actor in disguise, pretending so as to gain the community's trust.
What do you get? An insular, paranoid community, resistant to change, distrustful of new people, ruled by a mod clique with their own agenda.
I don't know enough about Hexbear to make a judgment, those are just my general observations, but from little I've seen I think it is happening there too. The whole "I wasn't lying to you users! It was all a sneaky ruse!" bit is actually sus, feels like damage control after being found out. The HB mods have clearly made their decision without the community and now they're trying to find a way to frame the change so that it doesn't piss off the userbase and result in them losing power or worse losing the userbase over whom they lord over. I haven't seen an apology to the effect of "maybe we were wrong to delete the community" or "maybe we should have consulted the userbase", it's all "sorry we handled it poorly" and "I'm sorry we're bad at communicating!" Very disingenuous.