I agree with you that the Marriott policy states that silvers are not auto-upgraded. To be clear, I was never auto-upgraded. I simply asked if they would be willing to put me in a gulf front room, and they always said yes.
I chose the word "policy" specifically because this was the word the front desk clerk used. Whether it was "practice" or "policy" it was something that this resort consistently did for the past 6 years, and now they're not doing anymore.
I also don't think they were ever in violation of the Marriott policy by upgrading silvers, they simply were choosing to go above-and-beyond the bare minimums required by Marriott Rewards. I think resorts that choose to do that should be encouraged, not punished!
I think there was a post a while ago about how Marriott was cracking down on Concierge Lounges that were offering breakfasts that were too elaborate, or something to that effect, forcing individual properties that WANTED to exceed the standards to scale back their efforts. I think everyone here was pretty upset by that move in the name of consistency.