I doubt this is terribly effective. People who really want to be shills or brigade will use tricks to get their vote count up just like they do on reddit. They'll post pictures of cats or dig something up on wikipedia to post to /v/todayilearned, etc.

It's not perfect, but it requires more effort on their part, and I don't think submissions alone can get you past the threshold, it's the comment points (CCP).

OTOH, those of us who just want to participate without playing the system are shut out of the voting.

You're only shut out for so long, and in a ways you're saying the system somewhat works. Don't worry, people are pretty generous around here with upvoats.