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.
Here’s an idea: adjust the weights of votes by how predictable they are.
If account A always upvotes account B, those upvotes don’t count as much—not just because A is potentially a bot, but because A’s upvotes don’t tell us anything new.
If account C upvotes a post by account B, but there was no a priori reason to expect it to based on C’s past history, that upvote is more significant.
This could take into account not just the direct interactions between two accounts, but how other accounts interact with each of them, whether they’re part of larger groups that tend to vote similarly, etc.
What if account B only ever posts high quality content? What if everybody upvotes account B because their content is so good? What if they rarely post so it would be reasonable that a smaller subset of the population has ever seen their posts?
Your theory assumes large volumes of constant posts seen by a wide audience, but that’s not how these sites work, your ideal would censor and disadvantage many accounts.
If an account is upvoted because it’s posting high-quality content, we’d expect those votes to come from a variety of accounts that don’t otherwise have a tendency to vote for the same things.
Suppose you do regression analysis on voting patterns to identify the unknown parameters determining how accounts vote. These will mostly correlate with things like interests, political views, geography, etc.—and with bot groups—but the biggest parameter affecting votes will presumably correlate with a consensus view of the general quality of the content.
But accounts won’t get penalized if their votes can be predicted by this parameter: precisely because it’s the most common parameter, it can be ignored when identifying voting blocs.