A Diagnosis is a big grey area. For example, 'Impingement Syndrome' as a diagnosis is just a joke, in my opinion. Same with 'runners knee' and things like that. "Piriformis Syndrome" and 'patella tracking disorders' or what ever they call them. J ust makes you treat them like conditions such as Asthma - deal with it.
Shirley Sahrmann, a very well respected physical therapist, makes the diagnosis based on the movement that causes pain. For example, if you have lower back pain which hurts when you round/flex, then you have Lumbar Flexion Syndrome (did i just make a diagnosis?

). This is actually a great system of classificatin because there's no ifs or buts with the diagnosis, and then treatments can be monitored, tracked, and organised much better than they previously have been.
A diagnosis doesn't help you (the lifter) much. You're as well calling it 'sore knee syndrome'. Or something. Specialists use it to help determine the best course of treatment. People get far too hung up on getting a specific diagnosis. Just find what's weak, and stop doing what hurts. If you're not going to find someone to tell you what's weak, then you better start studying, so you can find out for yourself.
I actually never recommend that people with typical weightroom aches and pains go to a GP. I actually advise against it.Nothing against GP's, I just don't think it's their thing. And, the typically accepted model of dealing with such issues is completely symptom based, and that doesn't help me get back to my previous PB Squat, for example. Maybe you have a far superior health system across the pond or something. Over here though, in terms of Physiotherapy, we're still stuck in the 80's.
I do believe that EVERY lifter should see a GOOD manual therapist every 3-6 months. SOunds stupid saying that for pain free people, but, onlyuntil you realise you do the same with your car (regular service) which can be replaced (you're body can't).
Guess what i'm saying is, is that I see your point. But I disagree that if someone goes out and get's a 'Diagnosis', then everything will work out. In my opinion there's nothing wrong with helping people take ownership of their problems - teaching them about balanced training programs, pointing them in the direction of good information, and recommending that they seek out a specialist to manually check things over.
KPj