The easiest thing to do is look at reports on FT in the respective hotel master thread - if someone was denied lounge access, they'll be an angry report about it. You shouldn't expect lounge access at any RC. Some properties will grant it even when they don't have to, and some will provide evening happy hours! No reason to complain about properties that go above brand standard - think of it as a happy surprise.

This also isn't a Marriott-specific problem - there are Hilton brands with lounges that don't give access to Diamonds (WA), and there are Hyatt brands that sometimes have lounges and sometimes don't.