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.
My perspective is that at least now it's out in the open.
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.
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.