It's just funny. I usually associate 4chan as primarily shitposting. Memes and offensive-stuff-for-the-sake-of-being-offensive and porn. You don't generally see mathematical work being done on there.
Math stuff was very strong there, I think you just never visited this site!
I could be wrong, but I think that the average non-active-4chan-user associates 4chan primarily with /b/.
B has a tenuous grasp on reality as a whole, but individual comments and posts can be charming, informative, whatever. I used to read the nightly AI threads where people would ask "how did you..." And sometimes receive answers. I even asked a question about some new model I had not looking right and someone said "VAE" and I fixed the problem.
I don't recommend any chan unless you're the sort of person that doesn't flinch at cop videos, gore, extreme impurity, and potentially illegal topics.
There is gold there, but you really gotta dig in the excrement to find it. For most, that's probably not worth it.