Exactly. I've heard timeshare salesmen use the same argument, essentially saying that if you rent out half of the timeshares (that they want to sell you) for twice the maintenance fee, the timeshares are basically free.
No, that statement by the salesmen (which I have never had said to me) is not true about renting. But, in the example, each year you rent out at double the MF, you recoup a portion of the investment/purchase price in the amount of the rent in excess of the current MF.
If you buy a HRA timeshare today for $15K and you can make $3K per year over the maintenance fee, you will break even in 5 years. If you go to HRA every other year and rent the other year you will break even in 10 years (and have 5 years worth of great vacations). Still, there are better ways to use your assets, i.e., the market is up lately (but, it also can go down).
Most people are too impatient, too risk avoidant or do not have sufficient assets to stay the timeshare course. So, they will not benefit by holding for 10 years because they will not rent every 1 of 2 years for a high MF timeshare with an advantageous rental market. I'm in for the long term. Admittedly, I have been forced to be in for longer than I thought I would because the timeshare market tanked about 4 years ago.
What makes the Starwood brand attractive to me is the overall flexibility it provides. I can vacation at pretty nice places I own at. I can trade to other places (like WDW) internally. I can trade through II to other nice places or back into Starwood. I can bank StarOptions for later use. I can rent my high MF week at HRA for double the MF. I can convert my low MF, low rental weeks at Lagunamar from StarOptions to SPG Starpoints and stay at luxury hotels and my cost will be 1.6 cents per Starpoint or make a further conversion to air miles for 1.25 cents per air mile (or much less than that if the airline is giving its own bonus, 50% or, sometimes, even 100%).
All of these opportunites can, if used judiciously, give me value - monetary and otherwise. (I just returned from a great 2.5 weeks at WDW. I arrived and for 5 days couldn't get rid of my office tension, but I am now refreshed, relaxed, tanned and ready to get back to work - until my next trip. How do you value that benefit? I am at the age and career level where I measure time by how long it is until my next trip.) It's the Starwood package of opportunities that, for me, gives more value than looking at each opportunity in a vacuum. But, I can only speak for myself. For many reasons, your usage and circumstances may vary and, so, YMMV.
Enjoy your timeshares! Salty