Of course, falling back on a diagnosed condition and using it as a crutch or an excuse for bad behaviour can be awful. I used to know a person with BPD, who absolutely loved being able to let herself off the hook for terrible behaviour. She would easily make friends, and sometimes would keep them for a few years. But eventually, one by one and sometimes in groups, they would cut her out of their lives because she was utterly toxic and selfish. So naming your problem can be positive or negative, but I think that depends on the nature of the problem.
I think my teenage years would have been easier if my family had been willing to talk about our anxiety rather than just pretend it didn't exist.
There is of course a danger that the diagnosis becomes an excuse - which is a particular problem with something like social anxiety where (at least in my experience) the only path to improvement is to face your fear and do whatever you're anxious about.
I'm quite concerned about the rate of medication being prescribed these days, often as a band-aid fix when people really are in need of serious life/habit changes. But I'm really surprised by the amount of people in this thread talking down on psychology and psychotherapy.