The actual format of tumblr blogs/whatevers prevented me for a long time from even realizing these nuts were serious. I'd occasionally see stuff transplanted from tumblr into cringe threads, usually so extreme and stupid that I just assumed it was trolls manufacturing these things. Surely, nobody actually acted this way. I think it was looking at cuteosphere/dragondicks and associates that I realized holy fuck, these people are serious.
I think the sheer aesthetic horror of tumblr may serve to drive away most sane people. It's not merely the words on the page that are offensive and crazy looking. It's the format, the look and feel, that is like listening to a symphony of a dozen people dragging their fingernails down a blackboard. Over and over again.
I find my eyes glazing over even trying to read this crap. Why does it look so BAD? Why is this popular?
It's not mere ugliness. I've spent a fair amount of time on *chans of various kinds, and they're generally pretty ugly. But at least you can read enormous amounts of (usually godawful) text in a legible font at absurd speeds, pick a theme that fits your ambient lighting, add custom CSS, etc. I can't imagine ever willingly spending any amount of time on tumblr.