Everything about Steem content is subjective. None of the voting on Steem is objective in any real way. Even automated bot votes are done because the bot owner/developer subjectively believes that is a 'good' way to vote. This is all both by design and unavoidable. People downvoting in a manner that they, subjectively, feel is best is how things are supposed to work.

I'm actually not, personally, someone who is terribly hung up about self-voting. But when others do feel that way, that is their valid opinion, and it is perfectly okay that they act on it.

Be clear on this though: There is nothing objective going on here, ever. All upvotes and downvotes are subjective.