The first milestone on that path was Milo Yiannopoulos. As outrageous and offensive as he was, he was actually a step above everyone who had come before him in terms of visibility and respectability – at least nobody expected him to shoot up a school or anything. The second milestone was Jordan Peterson, who was an obvious step up in respectability beyond Milo. There was a really interesting period in 2016 when the media was trying to decide whether to unite in character-assassinating Peterson the same way it had character-assassinated all previous people in this space, or treat him as some sort of interesting and potentially sympathetic phenomenon, and it decided on the interesting phenomenon angle. After that, being anti-SJW lost about 90% of its stigma, to the point where people would roll their eyes instead of freaking out. This New York Times article on the Intellectual Dark Web essentially turned the semi-respectability of anti-SJWism into common knowledge, and makes a fascinating contrast with the TIME article on MRAs linked above.
The whole process was a very clear example of a respectability cascade. There’s some position which is relatively commonly held, but considered beyond the pale for respectable people. In the beginning, the only people who will say it openly are extremely non-respectable people who don’t mind getting cast out of normal society for their sin. Everyone attacks them, but afterwards they are still basically standing, and their openness encourages slightly more respectable people to say the same thing. This creates a growing nucleus of ever-more-respectable people speaking openly, until eventually it’s no longer really that taboo and anyone who wants can talk about it with only minor stigma. It’s the same story as atheism, gay rights, and a hundred other things that were once taboo but eventually became mainstream.