I think the hotels blocking rooms also has something to do with the "points advance" option at Marriott. I am holding a couple points booking (in Maldives and Bali) not knowing which one I will be going to (still waiting for flight availability for December). I don't have enough points in my account for both the reservations. I read in another thread about someone booking rooms at W, Westin, St Regis in Maldives. the hotels probably don't realize that the probability of cancellations given points advance has gone up (and they probably also don't realize that people are booking without points in the account). I do sympathize with the hotels reacting by blocking rooms knowing Marriott won't enforce the no-blackout dates policy.
I actually quite liked the old "you need to have the points to book" policy at SPG, that came with real no BS no blackout policy. Love the days when SPG made the hotel open up inventory when the hotel played tricks.
I am LT PPE (hopefully, when they get their act right) with 70-90 business stays annually, but will be limiting business stays at Marriott given the nonsense about no black out dates. I feel silly to say this (would have never said this in the old SPG days) but Hilton is looking a lot better.
they should call it "no blackout dates" and in fine print indicate "we have no planned failure of electrical power supply days".