Tbf, I agree with you that a lot downvote whining is a lazy attempt to save a bad argument, but regarding this:
> Typically, when people get downvoted, the downvotes are for the tone of the comment - ad hominem attacks
Downvote and their purpose has come up a few times and generally the seems to be a consensus seems to be that downvote=disagree is 100%, legitimate, citing some quote by PG. And if you go to certain a threads (highly political ones), it's not uncommon to see some of the more reasonable comments greyed out if they even remotely challenge the zeitgeist of the current thread inhabitants.
This also works the other way around. You can be a complete dick and violate half the guidelines and end up highly upvoted if enough people agree with you. I know because it's happened to me.