Edit: obligatory explanation (thanks mods for squaring me away)…
What you see via the UI isn’t “all that exists”. Unlike Reddit, where everything is a black box, there are a lot more eyeballs who can see “under the hood”. Any instance admin, proper or rogue, gets a ton of information that users won’t normally see. The attached example demonstrates that while users will only see upvote/downvote tallies, admins can see who actually performed those actions.
Edit: To clarify, not just YOUR instance admin gets this info. This is ANY instance admin across the Fediverse.
So no known user will ever have a desire to join. Malicious actors will dig out their votes and expose it publicly. Could be massively damaging. You cannot do that with other social media. Obviously those companies have that information, but they do not share it.
Facebook likes, Twitter likes, Discord reacts, LinkedIn reacts, etc. are all publicly visible. The only possible slight difference with this is that in some cases people might not be aware, in which case the issue would be that it is less obvious to a casual browser than Facebook’s “AncientMariner and 23 others liked this post” rather than that the likes are visible at all.
They could just make an account that’s not identifiable? Or only use their identifiable account sparingly. Or not have their upvotes be publicly damaging.