So basically how it works is that no one actually knows how good Fabinho is. People are busy, we have jobs and university and stuff so we don't have time to watch games other than United ones let alone start following a whole other league. So almost no one has watched Fabinho play apart from a handful of CL games where they probably weren't paying that much attention to his performance. So the way this hype happens is that people have to acquire knowledge by proxy, so instead of gaining first hand knowledge they get their knowledge of players second hand. So if say tomorrow we become interested in Bakayoko, people aren't going to go watch Monaco games back and analyse his performances, they'll just read what everyone else is saying about him and take that as their own opinion, similar to like politics and other stuff in life where it's difficult to acquire knowledge yourself so you read others opinions who you respect/rate and take those same opinions.
So basically the Fabinho hype was one big self fulfilling prophecy where people here and other places online started saying he's really good so everyone started believing it and the hype got driven through the roof. He may very well be good but the truth is 99% of people who say he's good won't have watched him nearly enough to know.
Also YouTube videos are bad for a player like Fabinho because his biggest effect is how he allows the rest of the team to perform. He's not flashy he won't be pulling off great passes or scoring loads of goals but his positioning and breaking up of play will allow the rest of the team to flourish so that's how you judge a guy like him. Similar to Carrick, watching videos he wouldn't seem that special bar a few nice passes but the influence he has on the team is huge.