I can answer that in part: they have developed followings that cannot be instantly recreated elsewhere. Social media is a huge part of their business model. No

I can answer that in part: they have developed followings that cannot be instantly recreated elsewhere. Social media is a huge part of their business model. No, it's not a good idea to have your business model depend on somebody else, but many would simply have failed to get going without it. They put enormous effort into collecting followers. I know people who absolutely detest being on Twitter but their livelihood depends on it. Usually, these are small concerns, without significant advertising resources. They developed their followers by building up relationships over years, and can't afford to do that again.