Comment mentions and levels

Can we please get rid of the three level thread limit? Right now it can get very confusing when users reply to each other and you have a thread "depth" limit (3 here).

I think that limit is a mistake, just make the indentation smaller, and use colors to differentiate them. Move threads to a different view if they get too deep.

YouTube does that, too, except there you only have 2 levels, comments and replies, but on YouTube they at least automatically pre fill the comment field with the username of the person you're replying to.

So if you don't do away with the limit, please at least enforce mentioning someone when you reply.