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 was kind of joking, but now that I think about it isn’t that better? The problem isn’t really advertisers having your data, it’s companies doing skeezy things to be able to make more money with your data.
This way, instance hosts are free from that incentive and can just focus on making a good website.