I didnt say that. What I said is as soon as a player has obtained the needed skill points for the next star whether you have applied them or not to the player, the development progress that a player makes is slowed down.
So when a player on 69-70-70 with 4 skill points to spend gets his 5th skill point and the manager does not choose to apply those skill points yet, the players development slows down for his training.
I found that 2 seasons ago when I was power training Alex Zidane from 7* to 8* and he had some unused skill points and hes development slowed down because he had enough points already to take him to the next star.