I believe the principal reason blockchain based social networks will eventually take down all current mainstream social networks is that with blockchain powered social networks, the rewards are put in the hands of the user.

Take facebook for example, millions if not billions of interactions a day and all the profits goes to Mark SUCKerberg and his board and the users get nothing when the users are the ones generating the content, its outright stealing! and on top of that not only do they take all the profits but they are so fucking greedy and fucking corrupt that they go ahead and sell you to the best buyer! they sell every little piece of data they have on you.