In comments, I mentioned that comments aren't mandatory on Stack Exchange, and that there almost 800 questions on Stack Exchange Meta about this issue. In general, the mechanic that applies is that people can do what they like with their votes, with or without comments.
The exception is serial voting. However, my personal guess (I have no inside knowledge) is that it's not too hard for a serial voter to bypass the system if they're aware of it, so it's not foolproof.
While diamond moderators can see some aspects of vote history, going on a witch hunt strikes me as a solution that's worse than the problem. SE moderators may have access to data that diamond mods don't, but again I'm not 100% convinced yet (as much as I am seeing a pattern) that the ends justify the means.
My community-based suggestion is this: let's draw attention to questions and answers that we feel are drawing unwarranted downvotes. Anyone with over 500 reputation on our beta site can view vote count totals by clicking on a post's scores, and as a community we can choose be more aggressive about upvoting things that we feel have been unfairly targeted.
Everyone has their own personal criteria for how to apply their votes. In the interests of furthering this discussion, here are mine. I tend to upvote only questions and answers that have helped me personally, or that really stand out in some way. I typically only downvote questions that violate the basic tenets of our help pages, or that show zero effort. I rarely downvote answers unless they're off topic, preferring to flag as "should be a comment" or "not an answer" when appropriate. However, voting is a somewhat subjective thing, and there are certainly other ways to apply the useful/not-useful metric for voting.
If the community as a whole, including myself, starts upvoting answers that are considered useful in a broader sense (rather than just to ourselves), that will result in more total votes. While I'm not excited about the prospect of reputation inflation, I don't think it will ultimately harm our site to bring more attention and differentiation to questions and answers provided that people continue to vote honestly, and vote both up and down!
Bringing attention to questions and answers that need attention or improvement is certainly within the spirit of Stack Exchange, and could benefit PMSE greatly. It would also serve to trivialize the recent spate of across-the-board downvotes by making them statistically insignificant. However, encouraging more voting also runs the risk of increasing downvotes as well as upvotes, but while this may change the current dynamic of our site I don't think it is likely to harm it. Counterpoints on this concern are welcome, though!
Notes on Voting
It's worth noting the following:
- Upvotes are worth more than downvotes.
- An upvote on answers is worth 10, while a downvote is worth -2.
- Downvotes on answers cost both the voter and the poster.
- You can upvote/downvote more than one answer per question.
- You can earn towards the Sportsmanship badge if you upvote other answers to a question after you post one of your own.