Every doctor/therapist chooses patients, that's what specialists are for and a psychiatrist is a specialist but there aren't any other ways to narrow down what they're good at. I remember when I was visiting my GP (a literal GP I was visiting as a teen for my acne so she was playing "dermatologist") and she got a phone call and took it and she said to the person on the phone, "I don't know, I got a "C" in setting bones" and I suddenly realized that doctors aren't good at everything anymore than you and I are. They work with certain types of people and certain types of problems and have certain amounts of time (if he thinks you need 2 years therapy and he only has 6 months, you won't fit). It's a bit like he's a company looking for an employee and you're on a job interview :-) Not everyone has what he needs and likewise, he may not fit YOU!