One thing is time dedication, the second one is have an amount of anti-players. And this is my own opinion.

One of the most factible things for sure could be just close the training for 8* for non promoted teams and with skill limits the game could recovery the sense again.

We should remember that the GK training was a bug that wasn't fixed properly and since then seems people feels authorized to exploit the game as if they were in a party with Ronald McDonald.