One thing you have to keep in mind is that for a lot of younger people these platforms are the internet. The more tech savvy among them are probably going to branch out and try new things, but the majority don’t know anything else about the internet besides these platforms. The rest of the internet may as well all be considered “The Dark Web.” The average person already has difficulties with technology outside their little bubble of knowledge. It’s the same reason people stick with certain devices and software like Linux vs Windows or Apple vs Android when there is a plethora of alternatives. In a sense, why fix what isn’t technically broken.