Eighteen-year-olds play 'major league' tennis. Eighteen-year-olds (well, now 19-year-olds) play in the NBA. Sixteen-year-olds win gold medals in the Olympics.
Bryce is better than anyone else we have. That's just the way it is. The only reason why he is not playing in the bigs is because of $$$$$$$$$.
The one thing that is missing in all your examples is that none of them have a 100 MPH fastball coming at their head teaching you a lesson about respect in baseball. Thats what everyone is trying to say about growing up and being mature. Keep up with the antics and he will get a high hard one from a Veteran pitcher that will prove a point.