The main problem is that timeshare developers never define "commercial activity". Even in all of wyndham's actions against mega renters, they haven't defined what it is. THis leaves the interpretation up to the developer.
I agree, that is a huge problem, especially as it leaves wiggle room for salespeople to entice prospects to buy more on the premise that they can rent to cover costs or even make money. I do have to say Marriott goes a *little* in the right direction when they do state examples such as a "pattern of rental activity," but even that is not clearly delineated, and of course the salespeople don't even mention that prohibition. And what constitutes a pattern?
I have ZERO objection to someone with a fixed week renting it out. Have at it, you own that specific time and therefore no other owners are competing with you for it, whether you rent it, stay in it, or let it sit empty.
I also have no problem with someone who books a prime week/location with truly every intention of staying, and then something comes up, so as a one-off they rent it out to at least recover some of the MFs rather than let the unit sit vacant. But how do you prove they really intended to stay, and how frequently can it happen before it's no longer considered a one-off for that particular owner? I don't have an answer for that.
But for those who book prime inventory with either floating weeks or points specifically intending only to rent, I have a lot less sympathy. Timeshare are set up for people to purchase recurring vacations for themselves and their families, not to facilitate vacation rental-lite companies. Those who suck up prime weeks strictly for profit are doing so while having everyone else subsidize their business, because they get to rent out prime real estate at prime times but don't have to carry the costs of the property all by themselves, specifically times they wouldn't be able to find renters. If someone wants to run a vacation rental business, go out and buy (or build) entire properties themselves and carry all the associated risks and costs themselves. Otherwise, owners fully intending to stay themselves (or gift to friends/family) should have first dibs. But the problem arises of how do you sort out who is who, and at what point do you say it's ok for the profiteers to go ahead and reserve? Of course it's all rhetorical, we all know it's never going to happen.
It's a very complex issue with no easy solution. Go too far in either direction, whether completely permissive or totally locked down, and you're going to upset somebody.