Is La Cantera just a training grounds for other teams?

Real Madrid has made some big money signings this summer. The latest being Fabio Coentrao. As a fan of Fabio and the Portugal National Team I am excited about this signing. But if Real Madrid keeps signing all these so called “stars” than why do they have La Cantera? Real Madrid must have some experienced players that can provide leadership and knowledge to the younger players, but why won’t they promote from within? Real Madrid spends the time and money developing these players but seems reluctant to use them at the first team level. Instead the team loans them out or sells them. Now I agree with loaning out the young players so they are able to get experience at a higher level when a spot is not available within the first team. But when there is a spot they need to be given a chance. Many of these young players go on to other clubs and become stars. A perfect example of this is Juan Mata. I could only imagine the contribution he would have made to the team if he had been promoted. The current crop of La Cantera players definitely has some future stars in it. I can’t wait to see Morata and Sarabia become the amazing players that they have been trained to be. I just hope it’s with Real Madrid.