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.
Not all instances require email to sing up, I’m signed up without one.
Oh whoops, I deleted my comment almost immediately but it seems like you could see it and answer anyway. Yeah makes sense that it’s not an all-instances thing, it was very weird UI-wise because it said “optional” but then the address still came back when I left it empty, saved and refreshed. Seems like they might have forgotten to remove the “optional” label (or remove the requirement, either of the two).