You are certainly right, buying a small add-on is now a new strategy that many resale buyers are considering. However I don't think this was their main goal.
A few years ago the resale market was somehow obscure, just a handful of brokers and not much information on the Internet. Now anyone with a smartphone during the tour can open a browser and look for
DVC and chances he'll read about a resale market are pretty high.
Disney wants a way to say them: if you buy resale you're not really a owner. You cannot do this and you cannot do that. Limitations they introduced a while ago weren't as effective, everywhere you could read that they were a bad use of points anyway. They want to give people the feel they could be second class citizens. We are not talking about people reading this forum (who on average know more than many guides about DVC) and understand the real value of perks, but people who could buy on emotions during their trip.