Lemmy caters particularly well to the doomer crowd, since it presents an alternative to corporate-owned social media. Doomers have a lot of overlap with leftists(or liberals or whatever), and this causes a feedback loop of depression and anxiety. Consider two people; the leftist and the doomer:

-The leftist gets mad about something and posts a few articles

-The doomer sees this and reposts it with a more fatalistic title

-The leftist sees the new post and becomes more outraged, posting massive walls of enraged text in the comments

-The doomer reads the first paragraph and begins wailing about how the world is ending

-This anger spills over into other posts and generally sours the mood for everyone involved

Because the doomer is incapable of viewing anything in a positive light and the leftist lives in a state of perpetual butthurt, they feed into one another and fill everybody’s feed with outrage and despair.

Swap the leftist with alt-right and you have 4chan circa 2017. Let it fester for a few years and you have a machine for churning out political extremists.