Google+ started with a requirement for real names didn't it, no adopted identities. They stuck with it for quite some time.
IIRC it did largely cure YouTube comments. But, it damaged engagement, so ...
For Youtube, these kinds of comments threaten to alienate advertisers. Comments only have a miniscule impact on viewer retention and engagement, so if the actual business is threatened by comments you just get rid of the comment system.
Like the big game companies and their kiddie casino business model, it will eventually be slapped down if they can’t control themselves first.
Did it? I don't remember that being true.
This is how I feel about fake new too. It's not exactly what you said, but if your business can't afford to moderate what spews out of it, then adjust your business or shut down.
If your company has a platform that is beyond your capacity to manage responsibily, then your platform needs to shrink, or be chopped up.