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.
If it becomes too big of a problem, instances will whitelist the most popular instances instead of trying to blacklist all the bad ones.
How would that work? How will new instances/servers ever get a chance to grow if the fediverse only allowed those who are already whitelisted? Sorry for my limited knowledge about fediverse but it sounds like that goes directly against the base principle of a federated space?
It goes against the base principle, but, at the same time, is something quite possible to happen if things get out of control. Decentralization is complex, and brings several challenges for everyone to face.