SystemD critics formed as a cult of anti-personality. This both describes what they are (people with the opposite of a personality) and what they are about (hating that shithead Lennart Pöttering, who is a German man who grew up in South America to his German parents if you're picking up what I'm putting down*).

Per the wiki, Lennart is well known for being a weird dick about things in the Linux ecosystem and using market power and dominance, rather than a more collaborative or tech-first approach, to push his and only his ideas forward. This rubs people the wrong way, especially in a community predominantly built on the opposite ideals, leading to the universal hatred of everything he's ever built. But it makes creating distros easier so people deal with it.

Today, he spends his time working for Microsoft and refusing to acknowledge vulnerabilities in his overly complex standards-incompliant code.

SystemD haters are of course just jealous of his ability to be completely free of self-doubt.

*To be clear I have no evidence of this and it's probably not true, but it's 2025 let's be honest nobody cares if it's true or not