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.
I can’t just spin up a website and automatically get that info from other websites, but I can spin up a lemmy instance and get that info from everyone it’s federated with.
I agree, someone has to store and maintain your data, but giving all instances access to it is a risk that could be avoided