It's not a great one. You can blame anyone's shortcomings in the NBA due to the "fact" they had no mentor, yet most players can overcome it if they care enough.
I don't think it's blaming it all on this one thing. It's just stating "Hey, Kanter has lacked this one aspect, maybe that is a signal that there is room for improvement". People here are acting like it's a crazy thing to say or a bad observation to make, it's not.