I do not agree that I have stolen that many pops because these skills are also essential. Quite many seems to ignore to train these skills which why it is so common to see players with really nice skills that is pretty useless at the moment because they lose a lot of capacity from refusing to train team training.
In principle you are correct though. Team training probably lose less in efficiency at older age than other skills and could therefore be put on priority later on if you want to have an optimally trained player. You do not lose 10 skills in efficiency from team training though. I suspect at most 4-5 skills lost if delaying team training, probably much fewer, a little higher estimate as they drop these skills faster when they are on a high level.
But the only point I wanted to make was that team training should not be ignored until the player reaches his cap and not to argue about it