You know, I think it would be fascinating to do an analysis, now that we have DVC 1 BR villas designated as 5 person units as well as the so-called 4 person units, of the actual maintenance costs of the differing categories of villas to see if the theoretical added "wear and tear" of a fifth person can actually statistically be shown to actually exist in terms of maintenance costs.
I agree in theory an extra person walking across a carpet will contribute to wear, as will an extra person flushing the toilet, and ditto for one extra person that may accidentally bang a chair in the wall and leave a mark or drop a glass of grape juice on the carpet and make a stain. But often such theoretical results don't show up in reality across a population as predicted. The problem is that there are often many confounding factors that gum up the predictions. For example, in the case of room "stuffing" (nice pejorative, btw) there's an assumption that when an item wears out, it's primarily caused by the number of uses or actuations. However, that's one part of the equation in many cases. It also assumes that the usage of a repairable item is depended on the number of people in the room. True, some things like toilets, showers, etc. may fall in this category, but many other things (light fixtures, appliances, linens, drapes, etc.) do not.
It'd be interesting to track maintenance costs for different DVC properties over time to see if there's a discernible difference in "4" vs "5" person facilities. Granted, you would also need to normalize for the age of the property and/or consider when it was last rehab'ed, but I think it would be an interesting analysis. My gut tells me that any differences would not be statistically significant. I would also guess that any incremental "wear and tear" by "stuffing" people would be exponential in nature instead of linear.
IMHO, you can argue the issue from a contractual/legal angle and have a bone to pick, but I'm not buying the notion that the "stuffers" are taking money out of your and my pockets. There are way too many variables in play to be able to make such a claim with any level of certainty.