Yea that's the problem i see with there program. While it offers some good stuff and even some features bonvoy doesn't spell out like early check in (though for marriott in practice for platinum or higher, I've never had a hotel try to charge me for early check in anyways), there's no guaranteed compensation for hotels that just don't honor the benefits that should be guaranteed.
Plenty of hotels in the bonvoy family like to try not to participate in any of the benefits - claiming the usual rhetoric - "we aren't a marriott bonvoy property, we are just part of their reservation system" - autograph collection and luxury collection in the USA i find are pretty notorious for this. Nice thing with Marriott is if they try that crap, as long as you know the rules, you can often get guaranteed compensation. If not from the hotel, from marriott directly. I got the $100 comp or more at a couple different luxury collections now. Particularly easy for the welcome gift, since a lot simply offer nothing, or if you ask for the amenity, they have no clue, so the amenity automatically becomes $100.
A few in Marriott have also negotiated to provide very little benefits but keep the booking system, and even got that in the terms, so its harder to get much compensation if you deny you benefits. (Bahamas Atlantis, and Cosmopolitan come to mind. )
Though at the cosmopolitan when I went, while most of the staff is completely unaware of the program (they know a bit about the casino program - the two kinda fight with each other), they do have a dedicated autograph collection check in/lounge area which are decently trained in marriott benefits. They don't fully honor the normal benefits, eg: no free breakfast, but they actually even do some stuff they don't need to, like offer late checkout (they are technically exempt since everything in the vegas strip is considered a resort). And you can still get free breakfast via virtuoso anyways. (And there breakfast is not breakfast, its a mega buffet brunch that will be more than enough even for a huge dinner, since it runs until 6pm).
They also tried to claim the platinum/titanium suite upgrade is "1 tier only" (And i asked for a 2 tier upgrade). Which is isn't - they didn't get that in the terms - titanium upgrade is the best room available, including standard suites or better views - they just put in on their own website, which simply does not matter - it only affects bookings done on their own website and I booked thru marriott. I simply agreed to the upcharge for the best suite, called marriott and then marriott contacted their managers, thus they waived the upcharge at checkout.
IHG does the guaranteed compensation thing too for people getting denied upgrades.
Hopefully wyndham adds some guaranteed compensation for hotels not honoring the terms. In the USA especially, fining each other is the best path forward to compliance. Money talks a lot louder than anything else there.