Well, the question is, which you presumably can't answer yet, is what do Gold/Plat members get, at full-service Marriott family hotels, for breakfast if the lounge is closed and there is no buffet in the restaurant? Presumably a voucher, but how much would it cover there?

IOTW, sometimes the buffet is "expensive" too, but if you're Gold/Plat it presumably doesn't matter.

While if you aren't and care about cost, then what matters is not whether there is a buffet but whether it's a good value. It wasn't a Marriott brand, but once overseas I was at a hotel where the buffet was $33ish continental or $50ish full (the actual price was in Euros), or for a tiny fraction of that you could go half a block outside the hotel and order a-la-carte breakfast at a restaurant.

So buffet isn't always necessarily cheaper than a-la-carte.