I agree he needs to play a lot more, and unfortunately for the lad we don't have a B Team system for him to play. If you look at the league cup thread I was furious he didn't start the final, so much so it kind of killed my enjoyment of the win.
Dalot's competition is 2 aging fullbacks, Sane was at Schalke. Martial had no real competition when he arrived at United (he's also potentially a WC player) and was much more physically developed than Foden. Phil has to get minutes vs. the Silva's, KDB and Gundogan, he's trying to break through more players of higher quality.
Time will tell whether he's right to stay at City or whether he should follow Sancho out the door. Honestly though when should he play, who gets dropped for him?
I completely agree with your last sentence, talent alone is not enough, as I posted above look at who won best player at the u17 WC between Foden and Kroos. There is zero guarantee he'll be world class.