Anarchism has a much lower "barrier for entry" than communism. A communist is generally expected to have read communist theory and have a basic understanding of capitalism and its contradictions.
A person can describe themselves as an anarchist without any sort of reading or understanding of class structure or hierarchy.
So you get these "no vegetables, no bedtimes" anarchists (often called "anarkiddies") who vaguely understand something is wrong with the system, but haven't actually bothered to look into proper solutions, so they just declare "what if we get rid of the bad things I don't like?" and act like that is somehow political analysis, and not just a substitute for political theory, but is actually a better outlook than it.
I'm sure quite a few people here had a phase like that when they were younger, it does seem to be much more common to teens and young adults, people tend to grow out of it once they start to recognise how pointless it is (unfortunately most of them just grow into bog standard liberals, not actual leftists).
Of course, since it works as a barrier to prevent people from actually seeking genuine leftist thought, it's usually the only acceptable kind of "leftism" allowed in larger online spaces, since the feds who run them don't want people getting any ideas. I don't know if lemmy's mod team is actually full of feds, but they are trying to be exactly like reddit, so that includes anti-communist temper tantrums disguised as leftist thought.