With content creation platforms there is absolutely no way one person or even ten people at the highest levels could kill them by leaving. In fact, as has been shown on Youtube and Twitch it usually makes the platform healthier because there's not one monolith to develop a strategy around bootlegging from. There have been several dozen gargantuan channels and several hundred giant channels on Youtube who have either left or just stopped uploading and Youtube still carries on. Youtube isn't carried by the Mr. Beasts and FailArmies who grab forty million views an upload, it's carried by thousands of smaller channels who get less than a million views per video. With places like Reddit, Tumblr, and Imgur there are no giants, as everything is siloed so much that users in one community don't know much of what's outside that community, making it impossible for a handful of creators leaving to kill it.