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.
One other thing is that you can bulk create your own instances, and that’s a lot more effort to defederate. People could be creating those instances right now and just start using them after a year; at least they have incurred some costs during that…
I believe abuse management in openly federated systems (e.g. Lemmy, Mastodon, Matrix) is still an unsolved problem. I doubt good solutions will arrive before they become popular enough to attract commercial spammers.