So, federated network advantages here: you can always modify your instance's hosting code to patch this out, at least for the users on your instance.

What you cannot do is prevent other federated instances from publishing the votes submitted to content on their instance. But if you're accessing that content through your local instance, they can modify the upvote button to pop up a dialog saying something like: "The instance that hosts this content has elected to make usernames visible for upvote/downvote. Would you still like to vote?"

Personally: In many ways I don't mind. I'm on the internet with my real name. I don't mind being accountable for my behaviour online. I might be a little more cautious about upvoting something controversial or NSFW, but largely it wouldn't change my behaviour.