I don't have SPG Ambassador experience, having first qualified in 2019. But just looking at the objective facts, Marriott doubled the load on Ambassadors immediately after the merger, has now laid off most of them, and discontinued personalized Ambassador service. I don't know how that doesn't qualify as "gutting" the program.
I don't think that statement (Mayakoba as a "best" Hyatt property) would find much support in the Hyatt forum. I certainly wouldn't put it in that category. It's a very good value on points, with good restaurants, a good TSU suite, and a very generous breakfast benefit. It's not in the same league as most of the Park Hyatts, for example. I will say though that you'll be hard very pressed to find a Marriott property anywhere in latin america that provides equivalent value as a points redemption.