50+ 18yo HoF are pretty common.
I'm not saying that D1 NT or B3 levels prove it on it's own, but if its better for them training wise, then training wise it's better for everyone.
With that being said i agree 19yo have those pros of having one less season of training, being more prepared to contribute for the team immediately.
D1 NT or B3 needs the highest possible skill. Most users need the least amount of time and money to get to specific salary which they can still afford. 19yo have advantage both in skill and cost (youth trainer).