the fediverse is too complex to free people from centralized stuff

Not really, people understood email just fine, and fediverse isn't that different. The problem is there's a major subtle push to make anything open source look way more complex than it is. It's basically an open secret that microsoft did this with linux, and I'd be shocked if social media companies aren't doing the same.

it's extremely biased towards leftism

That's inevitable. Anything foss will appeal far more to the anti corporate/ anti capitalist leftist people.