Sure, and if a doctor is good enough, he can just start his own practice from the start and never have to sign anything since he never join any practice except his own.
That line of reasoning goes both way. If you sign something, then it was worth it for you.
>if a doctor is good enough, he can just start his own practice
It depends. Many instruments, such as PET in nuclear medicine, cost a lot. One have to work for hospitals/networks to help his/her patients with that instruments, no matter how good he/her is.
That line of reasoning goes both way. If you sign something, then it was worth it for you.