In my experience, most GPs wouldn't have a clue how to treat a musculoskeletal problem (and I've had one as a patient who admitted as much).
In my experience GPs get about 7 minutes to do a complete consultation and write any notes. I take 45 minutes to an hour. I couldn't get to the bottom of a complex musculoskeletal case in 7 minutes and my training in musculoskeletal issues is probably better than a GP would be expected to have.
That was very stifling as I wasn't allowed to teach the students to think outside the box, which you need to do to solve complex musculoskeletal problems.
Can you explain why you think it's necessary to think outside the box when solving complex msk problems? I am of the opinion that there are no complex msk problems, merely complex solutions looking for a problem. I go for a logical approach to diagnosis and treatment and keep things firmly in the box - works great for me and my patients.