Works pretty well on Reddit.

It's not perfect, but reddit threads sorted by "best" are a sight better than threads sorted by "new".

Upvotes-only wouldn't get you the same effect, since "best" is about the ratio.

Honestly twitter should implement downvotes and just copy reddit's thread-sorting system verbatim.

Finally, I swear I saw downvotes on the Twitter app some time in the last few months. Unless it was an April fools joke, it was briefly a real feature! What happened?