I came across this thread which had some interesting interpretations and posits that ML grew as a function of anarchism's failure to recruit/organize:

My sincere answer for why tankies reemerged five years ago is that movements are social hierarchies and newbie teens don't want to compete for status in existing illegible/inaccessible spaces like anarchism, so they resurrected a dead/empty scene that had trappings of status.

See also leftypol & the dirtbaggers. Folks get converted on one issue and then recoil about being expected to also learn / change their opinion on a variety of other topics. Respecting pronouns?! Never! You olds are a joke! We're making a new movement with hookers & blackjack!

Most of the anarchist movement had sneered at and avoided the internet (seen as an insecure tool of civilized alienation). Also it was illegible, most of the shit we expect you to learn/accept we don't even write down. And getting involved? We're terrible at helping folks join.

But ALSO the anarchist movement got up its own ass. We derided the internet and avoided utilizing it effectively. We embraced illegibility as resistance, forgetting that accessibility is critical to undermining hierarchies. And we corrupted into playing internal status games.

So what do we ascribe the sudden uptick in radicalization?