There's also a culture of not knowing when to stop posting and touch grass - when all your friends are way too online and probably also rationalists and much of your identity and status is tied to online posting, you invest a lot in cultivating that social identity and signaling to your community, even to a degree that would look unhealthy to normies.
There's also rhetorical advantage in spewing so much stuff that you snow your reader under a blizzard; what's worse, some of that tends to be true.
Nearly every blog post I have read in this ecosystem, even the rare one that contains some good ideas, is painfully long and extremely tedious.You can take the truthest truth ever like "god does not exist". This statement is rationalist and true and short so the author is supposed to cry with a tears of happiness. But making a wisard to behave like this requires something more thorough to be sent. Maybe the author's post also has a chance to become a rationalist if it would be a little bit... longer?