The best part of the fediverse is that anyone can run their own server. The downside of this is that anyone can easily create hordes of fake accounts, as I will now demonstrate.
Fighting fake accounts is hard and most implementations do not currently have an effective way of filtering out fake accounts. I'm sure that the developers will step in if this becomes a bigger problem. Until then, remember that votes are just a number.
This was a problem on reddit too. Anyone could create accounts - heck, I had 8 accounts:
one main, one alt, one "professional" (linked publicly on my website), and five for my bots (whose accounts were optimistically created, but were never properly run). I had all 8 accounts signed in on my third-party app and I could easily manipulate votes on the posts I posted.
I feel like this is what happened when you'd see posts with hundreds / thousands of upvotes but had only 20-ish comments.
There needs to be a better way to solve this, but I'm unsure if we truly can solve this. Botnets are a problem across all social media (my undergrad thesis many years ago was detecting botnets on Reddit using Graph Neural Networks).
Fwiw, I have only one Lemmy account.