100% this. As soon as you fork a project, you are now responsible for the evolution of it (even if that's just merging in upstream changes). It puts a large burden on engineering teams to track changes and maintain the fork.
You don't necessarily have to fork it, just the possibility of the fork changes the game. It means that the original maintainer cannot shut you down. If enough people deem a fork useful they can work together.
Of course there's a cost associated with it. But how much is it compared to the risk of someone shutting a core element of your business down? You have to evaluate.