Maybe because you didn’t observe it happening. Reddit admins were busy as hell cleaning the place up. All kinds of rightwing subs like some of the incel gathering spots. Some for straight up Nazis like frenworld or whatever it was where they were using honk honk as code for heil Hitler. When the admins made site changes due to complaints about right wing subs, Chapo made the list because they engaged in similar activities with the main complaint being brigading other subs. Their mods refused to change to meet the new rules. The admins eventually removed some of the mods. They still refused to change afterward. Which eventually got them shut down.
Yes. They moved here. Have done the same things. Pissed many people off. Thankfully this time they can be easily contained due to how Lemmy works. They could just grow up and not be an embarrassment to the left. But that’s apparently too big an ask.