I think it's more that we're afraid of that specific Reddit thing happening where a joke thread quickly rises to the top of the comments (because it's easy to upvote without giving much thought), and "drowns out" the more thoughtful discourse, due to people just getting tired of scrolling before they get to the non-joke replies. (Yes, you can collapse the joke threads on Reddit, but if they're at all funny then you don't tend to.) And then this happens recursively in all the thoughtful top comments--they all get their own joke sub-threads as well.

I've had a technical workaround in mind for this for a while now: if we could annotate the "intent" of a comment--if we could say "this post is intended as a humorous aside"--then the sub-thread hanging off any joke-thread could be automatically semi-collapsed, such that only the root joke-post and a bit of the first reply would show. (Or collapsed entirely if you set "hide post types: {humor, ...}" in prefs.)

I'm not sure what the social ramifications would be, but I think it's at least different than the "hide different posts from different people" idea that creates filter-bubble communities--you'd be showing/hiding comment sub-threads based on something more akin to the "cross-cutting concerns" of Aspect-Oriented Programming, than on their message per se.