You can't just play youth for the sake of it, its hard to fit all of your academy player into the first team as then your squad would be fill with 30-40 players and its natural to put the more experiance players on it. A team's acedmey usually only has about 5-10% of its players that become first team regulars while the rest get sold on so they can play regular first team football in whatever league. Also some players don't have any patience , look at Stoch. He wanted first team football every week and always on the starting line up, we could not do this and had to sell him because when his contract ran out he would refuse any new deals - so it was better to get some money off him.