Earlier quoted context omitted.
If you're famous, you'll almost certainly have a twitter account, although there are obviously exceptions. The same just doesn't seem to go for YouTube. Creating content on YT is a lot more time-consuming than creating it on Twitter, of course.
This is why YouTube is a platform with value and Twitter isn't.
As a recent example, think of Pieter Levels (@levelsio). You think he would've gotten $10k first day sales on his avatar AI project without his Twitter account's reach?