That's the thing about trying eliminate voting. If comments essentially serve as votes, you actually get the worse kind of filter - the way the filth rises to the top on Youtube comments for example (Youtube sorts by most commented even though it allows voting - so hateful stuff remains even when downvoted).

The best solution I've seen for this is to have a separate subforum for highly contentious discussions, and anything with more than a threshold number of comments per hour gets automatically moved there and flagged for moderator review. Then the moderator can move it back, delete it entirely or just leave it in the separate subforum so that interested parties can flame each other in the fire pit instead of out where everybody else hangs out.