Not being welcome
Let's assume the existance of ContentMart, a big, centralized content platform, used by everybody. Let's assume three people who use it and offer content: Mr George (a far-right user), Mr Paul (a far-left user) and Mr John (who doesn't empathize neither with the far-right, neither with the far-left, he uploads content non-profit). And on other side let's assume the existance of two alternative platforms to ContentMart, both newer and with less popularity. By now, neither Mr George nor Mr Paul nor Mr John have knowledge nor means to create their own platform.
Beginning of the purge:
ContentMart begins an account purge to get rid of the users aligned to extreme ideologies, both far-left and far-right. Mr George will believe mistakenly that ContentMart chose to be on the side of the users like Mr Paul while Mr Paul will believe mistakenly that ContentMart chose to be on the side of the users like Mr George. Mr George finally finds the first alternative platform and will call their followers to join to that platform. Mr Paul finds the second alternative platform and will call their followers to join to that platform. It could be possible that Mr Paul or a fellow have tried the first platform, but by seeing it already occupied by the Mr George fellows, they'd quit and stay away from them. Mr John doesn't care. He's not like Mr George nor Mr Paul. The users who see his content is very general, or at least none of them looks like Mr George nor Mr Paul.
One day ContentMart bans Mr John. A change in the terms and conditions of usage of ContentMart is prejudicial for those who upload a certain non-authorized content and Mr John becomes a victim. He could try any of both alternatives to ContentMart but he will find both platforms full of users who with he won't feel comfortable. So Mr John will keep trying to use ContentMart. At best one day Mr John will have the knowledge and the means to create his own platform for personal use, but until the day this happens, or the day that the alternative platforms have a more welcome attitude with the Mr Johns around the world, they will keep prefering to use ContentMart.