To me, the trolling is deliberately done for the express purpose of being blocked and to force you to flee. See, what Alt-Right and other extremist types know is that they win if you leave. It leaves them with no opposition, which makes them seem normal to those who come in later. They see only the Alt Right opinions, only the Alt-Right interpretation of the news, their memes, and their content. There’s no (or only extremely muted) dissent. And as this happens at more places where teens/twenty somethings hang out online, they think such discourse is normal. They learn who you are from them, in a place where no one like you goes. If your first contact with activists is from trolls discussing a Breitbart piece in a place where no activists are around, you assume not only that the article is true, but that everyone opposes the SJWS. They’re sick, special snowflakes, they hate you, you ducking white male.
It’s simple. You control the image you create of yourself because no one challenges you. You can look reasonable even if you’re not — if nobody can call you out on your crap, point out the history of the person saying those things, or anything else.
The other thing is that I think joking about something will eventually swing your opinion to the content of the joke. When you constantly joke about stupid blacks, even if at first you don’t believe it, eventually you will. Because you’re constantly repeating it, even in a joke. You are constantly hearing yourself say in lots of different ways in lots of contexts, that whites are just better than blacks. It’s a sort of mantra — you repeat it enough, and eventually context doesn’t matter because your brain forgets the context. Eventually your brain thinks “I keep saying this, I must believe it. It’s probably true,” and because mr. Brain wants to be consistent, it incorporates that into your psyche as “I’m racist “ — probably not in those words, but in content. You no longer think those ideas are weird, you and your buddies online joke about it all the time, you think it’s true, and then the opposition sounds weird because it’s rare and unheard.