I wonder how much is due to lack of feedback? I went somewhere due to knee pain. After some time got a diagnosis and some exercises. Didn't feel it made sense, so I went somewhere else and got a better (the correct) diagnosis and got my issue fixed.

To the first PT, the only signal they have is that I didn't come back. If their assumption is it was because I got cured, they will probably give the same wrong diagnosis the next time someone shows up with the same symptoms.