I'll take my own scenario from the vacation I have coming up at the end of December (so stupid crazy peak pricing, yay!)
I originally booked a hotel off site for 4 nights/5 days, and it would have costed me a little less than $400 total. Then I thought about it, and thought that I'm going to do this once with the kids, so I want to do it right. As such, I changed it to POR, and my hotel bill went up to about $1300 for the same time period.
Now, if I wanted to exploit the loophole, I could get a space at the campsite (which are still available as of 10 minutes ago), pay $115 for one night, keep the old off site room, and I'd be paying a bit more than $500, and get most of the same perks as my stay on POR would have given me. I'd still have to pay for parking for the last three days, but still having FP+ open up at 60 days would be huge, especially during the holiday season. All in all, it would be about $750 I would have saved, comparing apples to apples.