If you were an graduating engineer and Microsoft offered you a contract, you would still likely try to market your services you say Google to see if they make a better offer. And Apple etc. No one sends their resume to only one company.
But what if Microsoft said "You can't do that because we have an agreement with Google that says you can't. Apple too. All the Big Boys actually, you can't work for any of them but us.
But you can go market your services to Jimbo's Computer Barn in Northwest Upper Butt Crack so...fair, right?"
You think that would fly in America?
In this scenario, Microsoft is the NFL. They are one company with 32 equal divisions all working very closely together.
Players are welcome to play professional football with other companies and apply to the Canadian Football League, the XFL or anywhere else they like.
Joe Namath signed with that inferior league the AFL
Jim Kelly & Steve Young signed with the USFL. Warren Moon played in Canada. That option doesn't exist anywhere in the world ATM.
But when the Saudi's, and their unlimited capital, come knocking on Patrick Mahomes door, or Josh Allen's, or Caleb Williams, or the next generation is f talent. The NFL owners will realize how precarious their position truly is.