Wether they want to see opinions they agree with or not is up to them; if they up moderate both things they agree with and those they don't they'll get connected to people who moderate the same way.
Trying to force people to moderate without bias doesn't work very well, a significant portion will always downmod things they disagree with and things like metamoderation only affect the most excessive raters. This way you limit the damage so the subjective moderations only affect those who want it to affect them.
Perhaps you will end up with most discussions containing people who barely ever even see eachother. Much like real life. Or networks of groups who like having meaningful conversations will form. But which one you'd be part of would depend upon your preferences, not on what random people you have nothing in common with think about a specific conversation.
And, perhaps, just perhaps, there'd be a bit less of screaming for censorship anytime anyone gets offended by idiots if the easily offended got separated from the rest.