OP, I guess I don't see your issue. For me, a 100+ night a year Titanium, my status means I always check Marriott first, but it doesn't lock me in. There are many locations in which I still choose to stay with other chains or independents.

I certainly don't expect my loyalty to Marriott to allow me to book any of 500+ non-Marriott hotels in London and have them treat me like a valued frequent guest. If I don't stay at a Marriott (or Hilton where I am Diamond), I make sure to book the room I want and pay for the benefits I want.