Two unrelated issues: one is whether psychiatry training per se can be proficient for therapy; two is whether specific psychiatrists can deliver combined treatment that is better than split treatment.
In general, psychiatrists nation-wide are not as well trained in psychotherapy as a PhD psychologist, and especially once you are in practice for a number of years, psychiatrist by-and-large no long practice psychotherapy. As an average psychiatrist doing average general psychiatry you would not aim for doing predominantly psychotherapy or combined practice. Much like a general surgeon would mainly do choles and appys and not aim for some complicated liver surgery. That's true.
However, in subspecialist settings, there are psychiatrists who are comparably more skilled and experienced in therapy than most general PhD psychologists for specific kinds of psychotherapy. For example, in my experience, with a fellowship, I'm a much better substance abuse psychotherapist than a PhD psychotherapy with no subspecialist training. Complicated patients who have comorbidities prefer combined treatment. Similarly, psychiatrists who focus their practice on borderlines and and have specific training on TFP/DBT, etc. are usually better therapists than a general PhD psychologist.
