This is certainly a problem, but I find it happening less on "special interest" boards. I don't think it's too far from Reddit in this respect. On /r/funny you might expect something like this to happen, with the top 2 comment threads being puns, or unenlightened comments. But on /r/EngineeringStudents or /r/compsci or /r/lisp ... (subs I vaguely remember) that's less likely to happen.

Right now on /leftypol/ there aren't many threads of what you describe. They do exist, but they aren't numerous. What you describe is more similar to 4chan's /b/, but even 4chan's /g/ has "tightened up" and is being steered more toward discussion (still with racial slurs but not entirely focussed on them). A notable exception is the "DESIGNATED SHITTING STREETS"/ "POO IN LOO" meme, though.

I don't know if these are just my experiences.

I hang out a lot on /diy/ and /out/ and some on /pol/ and behavior is definitely driven by board culture not technology, as the underlying technology is obviously the same. The worst I see is on /out/ is the mora knives nuts, sure I get that you like that knife for outdoor work thanks for telling us the 10000th time now go away. The worst I see on /diy/ is, well, nothing, maybe some half-baked electrical advice sometimes, well intentioned maybe but if you're doing something weird maybe wiring your own subpanel if you have to ask /diy/ how to ground it you should probably give the job to an electrician. The worst I see on /pol/, well no point going there here on HN, but you can guess.

I meant more as in 4chan and /pol/. Haven't gone to 8chan or /leftypol/ but I'm always interested in quality discussion. That's why I frequent Hacker News.

I think it happens less on special interest boards because there are less posts altogether on niche boards.

/p/, /trv/ - slow boards that have their own shitposts.