>much of what's posted on 4chan is ironic, deliberately inflammatory

This hasn't been plausible, much less true, for 10 years. I don't know how anyone can look at, for example, Payton Gendron's manifesto and say it's ironic. Were the bullets he fired ironic as well?

There is an entire generation of users, who are probably the bulk of users now, who were never in on the "joke" (if there ever was one).