Monopolies
Current platforms have a monopoly over your friend network.
The network effect—value added to a platform by everyone else being on it—is giving platforms like Facebook monopolistic powers to abuse their users and charge a high price in privacy while maintaining billions of active users. It’s not that they’re necessarily evil; any rational actor with a monopoly would do the same. Unfortunately, that means any other centralized platform is doomed to the same fate as soon as you and your friends switch, and the network effect takes off.