Yes, this is what forums and mailing lists used to do (well, they're still doing it, there just aren't as many).

When Digg introduced voting on links, it was initially seen as having way better content than the rest. And then Reddit did it with comments as well, and nobody looked back.

The main reason, I think, is that nobody read a whole thread. They look at the few top level comments (in upvoted threads) or at the last ones (in a forum/mail threads) and will reply to that - so that the quality of the whole discussion is determined by what people see first.

That being said, it indeed comes with a lot of problems of its own. Upvotes/downvotes favor hive mind thinking (you want to be loved, so you'll give people what they want) and mobs (if something is downvoted, you'll just add one more downvote).

A couple years ago, I went back to using mailing lists and it's indeed a less frustrating experience, from my point of view. But I'm not sure it's about the technical aspect, it may just be because there are just less people in it.

The ones with the shock value tend to get bigger though. Chronological ordering would emphasize either the first or the last comment, and given that these are two out of many, it's unlikely that either of them is the best comment.