On about the first page of Malraux's Anti-Memoirs he writes of asking a priest what he had learned from hearing all those thousands of confessions. The priest said, a) in general, there are no grownups; b) people are sadder than they appear.
I bet you'd get a similar answer from psychologists mostly because well adjusted people tend to not visit them.
Add a smidgen of bias in remembering and setting affecting the confessions, here's your full picture.
You're also making a selection bias, assuming people that see a psychologist are not well adjusted. It's equally possible that only well adjusted people seek psychological consult, while others are sublimating their problems.
I don't necessarily agree with that conclusion either, but I think it's worth pointing out. Especially when discussing emotional maturity.