The developers who created Lemmy are leftists, and they run the lemmy.ml instance. The lemmy.ml (.ml is for Mali, btw) domain was allegedly chosen because ML can also stand for Marxist-Leninist.
I’m not an expert on the subject, but lemmy.ml users are known for being tankies. People don’t like that.
However, some of you whipper snappers don’t know that those of us with really old accounts joined back when lemmy.ml was the most popular instance. I just like FOSS things.
Edit: added “allegedly”
I have not verified the validity of those claims. I’ll edit the post to reflect that.