Other than the techies getting emotional and screaming at Twitter, little to no one of the 200M+ people still using Twitter daily care to delete their account(s) and leave for something worse.
My perspective is that at least now it's out in the open.
I am very much in favor of premarital sex, but if the Pope is seen tomorrow in an orgy I'll certainly point the hypocrisy.
I don't even see them as competing platforms, they offer very different products via the same medium. Legally, I don't know if having such ToS would be a problem, but as a user I would find it extremely frustrating to not have to ability to discover content that YT seemingly doesn't want to focus on itself.