If developing young players is a big part of our model then we should always have 20 and 21 year olds on the books.
I've seen people citing Dom Thomas and Luke Watt but so what. It's as stupid as saying no more loans because of Connor Sammon or no more young English players because of Newell. There are always going to be more who fail than make it, that's the nature of the process. We sign plenty of total duds from outside the club to contracts, it's not the end of the world if youth development ends up with the players going to the lower leagues.