That doesn't come without a cost to those owners though, because it also reduces the trade power of the resort through reduced demand. For example, I avoid most (former) Diamond resorts, because (a) they have a resort fee that is north of $100 or close to $200 for a week and (b) there are usually other resorts that are just as nice (or nicer) nearby that don't charge one. I have to believe I'm not the only person who does this.
For GPX, it depends on the location. For coastal southern CA for example, the GPX resorts don't have much competition, so I will pay it if that's where I want to go. But the Makai Club, there are lots of equally nice (or nicer) timeshares just in Princeville, let alone on Kauai, and there's no way I'm paying an extra $175 to stay there vs. any of the others. This is also why I don't bother with the Orlando HGVCs, but will happily take an exchange into, say, Kings Land. I also don't mind the DVC nusiance fee, because they offer something unusual.
TL;DR: If you have something unique to offer you can get away with a resort fee. If you are Just Another Timeshare In The Area, not so much. Makai Club is definitely the latter.