I wonder if there's any data to support this theory. Could it be that onsite guests spend more time inside the parks, and use attractions more than offsite guests? Because they have done a great job of filling up their resorts year-round with "free" dining plan and other promotions.
That would explain why single digit increases in attendance "feels" like more than that. Maybe off-site guests arrive later (in general), leave earlier, may not plan as much so don't use as many attractions. Could be they leave to get dinner off-site, decide not to driver back in...for example. Just a theory, no idea if this is reality.
Also, keep in mind single digit increases in attendance add up after a few years. So, for those of us that don't go every year, or multiple times a year, could very well be that it's up 15% or more, which would be noticeable.
Again, the resort attendance is nearly constant. So even if on-site guests spend more time at the park -- there are approximately the same number of on-site guests in 2015 as in 2014 as in 2013. (they just are able to get the same number, with less discounts). No new on-site hotels have opened in the last few years. There has been a little additional
DVC, but not enough to bring a huge increase.
http://touringplans.com/walt-disney-world/hotels/number-rooms -- Disney World has 30,000 hotel rooms onsite. Assuming an average of 3 guests per room, that would be about 90,000 people at 100% occupancy.
So let's say they did increase from 90% to 95% -- that would be an increase from 81,000 on-site guests to 85,000. Spread those 4,000 people out between 4 parks, water parks, etc, etc... Maybe up to 2000 extra bodies in Magic Kingdom. That's just not enough to cause massive increased waits. According to touringplans, the jump in wait times is the equivalent of adding an extra 8,000 to 10,000 people to Magic Kingdom.
Now..... the 2% per year theory.... leading up to 15%...... The thing is, the jump is very very noticeable to people who do go every year. This is the first fall where the waits have been so ridiculous. I suppose it's possible that Disney World was able to handle the 2% increase each year after year... but then suddenly, this year... they suddenly crossed a threshold where the damn broke. Kinda.... Magic Kingdom can handle 60,000 guests with no issue, but as soon as you hit 61,000, it creates massive headaches.
As suggested in the touringplans article, the most likely explanation is some change in how Disney manages the crowds, but I suppose we can't completely discount that its due to some actual attendance increase.