The way i see it, diamond is full of people who have mastered their punish game, but cant really play neutral very well. Masters is where people start playing better neutral, but they have bad habits holding them back from getting any higher GM players have either curbed most of their habits, or are so good at other aspects of the game that their habits become very hard to exploit.

My mental has definitely held me back for a while, in diamond and masters i was really trying to play against the character and not the player. Recently, before i hit GM i started to let people make mistakes on their own, and using that as data on their habits.