I've never interacted or understood /b/ much but my impression of 4chan in general is that you kind of get a slice of humanity because of their rules + anonymity. Both the good and the bad.

But I've never seen anyone describe it as rejecting reality, nor have I ever got that impression from much that I've seen from there. It's mostly people fucking around, whereas the hard left you're referring to seem to be taking it a lot more seriously than most on /b/ (that I've seen, not much personal experience with it).