Alexander William Slater: "Why Progressivism Wins"

Interesting and fairly plausible, but I haven't thought about it much.
My pet hypothesis / partial explanation is: it encourages acceptance and suppresses dissent rather as Christianity does, by running a kind of moral ad baculum: If you don't accept the view, you're evil. Failure to accept the position doesn't just make you wrong, or lead you into error. Rather, criticism and disbelief are morally wrong in themselves.
Then of course you add the ordinary ad baculum: criticize or reject progressivism and we will make your life miserable. 
Fear of being seen as evil (or, as what's currently thought to be worse: racist) and of actually being evil combine to suppress dissent and fuel acceptance. It's a powerful combination.