1) The anarchist milieu has been burning off shitbags for the last few decades, and a lot of these banished folks fled to leftcomism, marxism, postmodernism, etc
2) The Bernie wave produced a fuck ton of marxists who eventually discovered that there's basically no power or community in tankie or leftcom projects, anarchists remain the majority on the ground
3) A fuck ton of college kids got radicalized exclusively online and flooded into discords managed by the prior two