Just to make things clear i am on complete disagreement with you on the youngsters topic. But just a look on this thread is enough to convince me you're actually right! The problem isn't just the management or the coaches. It's the fanbase as well. The whole organization doesn't have the patience to develop a youngster.
The issue isn't Radu of course, who's nothing special, but the mentality a youngster isn't allowed to make mistakes. You can find many videos of GK mistakes out there. Manuel freaking Neuer was getting laughed for his mistakes at Schalke. I can't even imagine (or actually i can) what would have happened to Donnarumma's career if he was making these mistakes at Inter.
If you aren't ready to support a youngster when he makes mistakes, then don't even bother playing him in the first place. Making mistakes is a part of a youngster development.
And for the umpteenth time, we didn't lose Scudetto because of Radu. We lost it because of De Vrij fuckups. We lost it because of Inzaghi poor subs. We lost it because we had no Brozovic backup and when he was missing we got utterly destroyed by Sassuolo. We lost it because Lautaro and Dzeko disappeared in big parts of last season. And, most importantly, we lost it because we became complacent after Perisic early goal at Bologna instead of killing the game.
I get people want a scapegoat for last season capitulation but blaming it on Radu is ridiculous. In fact, his mistake didn't make a difference in the end.