As another poster said, I dont think MP is ignoring youth. He wouldnt have played Kelechi against both Palace and Norwich otherwise. He just: (1) wants to develop them slowly; and (2) felt that a Navas/KDB/Sterling combination with Fernandinho able to venture forward was our best chance of winning the game. You can debate either decision, but I dont see how anyone can say he was clearly wrong (much less throwing puerile internet abuse at him). If Kelechi plays only odd minutes here and there for the rest of the season, then I for one will not be happy, but I dont expect that.
It is always tempting to throw a youngster in at the deep end, but there is a pretty significant risk of burn-out, especially when our standards are so high. Again, look at Martial. Pretty good start, but is fading as people get to know his play, and it's not clear that playing him every game is actually a benefit to his development.