I agree with the other comments. I think it makes the most sense to only allow submitters to rate games. Better yet, if there's an option for it, non-submitters should be able leave comments and feedback, but their ratings wouldn't be factored into the rankings.
I understand that the intent is to make sure everyone's entry gets played, but I don't think this would help that much. I feel like most non-participants who are only interested in a specific game would have the patience to play maybe ONE mandatory game first. I could see a lot of people giving up, or worse, start sloppily rating games, well before #50.
It's good sportsmanship to give different games a chance in a jam, but ultimately you can't force someone to play something they're not interested in.