Mine could be a minority viewpoint on this subject, but it is my personal belief that owners at any given resort, who already pay for all amenities on site in their maintenance fees,, should never be subjected to any additional "resort activity fees", with the minor exception of stand alone, extracurricular social events which are occasionally conducted on site (e.g., a lunch, Margarita Day, etc.). Anyone (owners included) choosing to participate in such optional events with costs should indeed "pay to play"; that's only fair.
However, I am perfectly fine with mandatory "resort activity fees" being charged to any and all (non-owner) "exchangers" and / or "renters" at any given resort. The additional income, going directly into resort coffers, presumably helps to stabilize maintenance fees for the actual owners who are already paying to keep that place running and well maintained. I do not buy into the reasoning that "exchangers pay maintenance fees too, just somewhere else"; that is a lame non-sequitur, IMnsHO. Renters, of course, may or may not be paying any maintenance fees anywhere.
Just my personal view and opinion, with which others might disagree.