If I vote something I'm expressing my opinion just like I would with comment, and those are not anonymous.
I get that people are worried about griefers and psychos, but anonymity is just a (poor) cure for the symptoms, not for the disease; users who don't behave should be banned, and if their instance turns out to be a detriment to the community, they should be defederated.
The anonymity we should ensure is the one of the person behind the username, to avoid doxxing and cyber-bullying.