To be fair, I agree with all of this.
I'm not concerned than Palmer or McAtee aren't good enough, far from it. Nor am I worried that Pep I am concerned that we will not be able to keep hold of players this good by giving them pitiful minutes when they are old enough to play regular football. You can get away with giving a 17 year old 300 minutes, but a 19 year old? They will be expecting more. Palmer and McAtee will look at Foden, the player they have been shown as the only current example of the youth system working and wonder why they are getting fewer minutes than Foden was, who was 2 years younger than they are.
I don't think age is irrelevant. If a player was still in the academy at 22 or 23 without making any significant first team appearances, would age still be irrelevant? Would he be at the "same stage of development" as McAtee right now?
Foden was promoted far earlier in his development than Palmer, you can call it the "same stage of development" but that is disingenuous. Foden never got to the point of dominating youth team football that Palmer and McAtee have gotten to because by the time Foden was their age he was a bonafide first teamer.