Because when you accept idea that sex is social construct, you cannot explain what is a women or man. I guess it wouldn't be possible to push this ideology without social media and different way of communication in our society.

Virtual world easily spread tribalism that could be around most ridiculous things we can think of, because of lack of confrontation with reality. IRL there would be laughing, denial, fear, explanation why those ideas are nonsense... But all of that is not there if you lock yourself in bubble of virtual people that share same ridiculous ideas. Of course they will eventually dominate field where they invest most of their time - internet.

We know from history (or China, Russia, North Korea) what was a purpose of control peoples tongue and what they should think about. We should learn from it. I still believe that this ideology is pushed by small, very loudly screaming group of people. Majority don't care.