Taking advantage of the system? Not when it is the only way the system works. Disney created the reservations system to work a certain way, a way which obviously does not meet the needs of a good portion of their customers. I don't think it affects a majority of their customers, but still a good portion. It makes a sort of logical sense - Disney World is a vacation destination, and in this case the word vacation means "a week or more". In order to get that shorter stay you may desire, you may have to book more days than what you originally wanted, then cancel the extra days a bit later. You get the days you want, Disney gets your money, everyone goes away happy.
I agree and most cancel within a couple of days of the original ressie so no harm no foul for the most part
Now, the one's I think are taking advantage are the ones who book a week or more at the Fort with absolutely no intention of setting up on a campsite. They stay at some cheap place off site, but because they rented a site at the campground, they get all the advantages of staying on the property, i.e. Extra Magic Hours, free parking, etc. Disney does nothing about it, because Disney got paid - what do they care whether the person doing the paying actually uses the site or not?
I disagree with this ... while I don't like it that is their right to reserve the site and use it however they see fit within the rules and consideration of other fellow campers even if they are not camping there. They could use the site just to park their vehicle and then go to the parks using Disney transportation or even to hold a family BBQ at for one day out of their reserved dates.