Posts are one thing, and difficult enough to spot/moderate. Vote manipulation is a whole different story. Burying a story you don't want to gain traction is easy in Reddit, and if the post ends up gaining traction you can easily change the discourse in the comment section by burying critical voices.

It's probably already happening on Lemmy, but it'll get much worse as the platform grows bigger. I have no idea how it could be stopped. Kbin originally started out not federating downvotes, with this challenge probably being part of the reasoning.