The pdoc at the IOP I was recently in I think overdiagnosed BP. There were some people that came in and didn't share anything in group that sounded like a history of hypomania/mania and they got a BP diagnosis and were put on meds (not that I'm a psychiatrist).
Although I am going to say that reading this thread does kinda make me doubt my diagnosis and want to stop my current treatment even though I know without it I would probably have been dead by now because it has helped.
My philosophy is that the diagnosis doesn't matter to anyone but the docs as long as the treatment helps more than harms