It's interesting because at our place, when we started doing heart surgery, there was an exclusive contract with one group of surgeons (from University of Chicago) to do OHS (open-heart surgery), and no one else could - even though they were on staff and could do other procedures.
When the relationship with U of C soured, another group had exclusive contract. After about 10 years, others were permitted to do OHS.
And, speaking of "economic credentialing," my (old) group had its exclusive contract not renewed in 2017, and everyone was out of a job in 90 days. Administration thought it could find similar coverage for less money.
Thought....