I must respectfully disagree with the above cited logic and conclusions.
A desirable fixed week, even at a "lower end" property can always be sold or otherwise transferred with relative ease --- and sometimes at a slight profit, even in a soft market (assuming that the exisiting ownership was acquired resale and not via developer-direct purchase, of course). Even in the worst case scenario (as per George's input above), a deedback of a decent fixed week to the HOA is often readily accepted. I also know (and knew when I purchased them, resale) that my weeks could always be sold at break even (or better) pricing.
Additionally, many floating week ownerships come with onerous reservation restrictions which devalue them considerably. In coastal SW Florida, for example, I own a number of consecutive fixed "Snowbird" weeks at so-called "lower end" resorts, whereas "floating" week ownerships there are entirely "blacked out" of the reservation process from about weeks 5-15, inclusive. In essence, "floating" week owners there have exactly zero chance of ever reserving a desirable winter week. If "floating" always meant weeks 1-52, your point might well have more validity --- but that just ain't how it is with many "floating" week ownerships.
In short, there are very few "one size fits all" generalizations which are universally accurate in the strange and wondrous world of timeshares...