Ok, I had to laugh at being attacked because I said I suspected most place holders are AP holders. I

Disney AP holders. It did not make me mad.
And I have had APs myself both at DL and WDW. I PREFER the DL parks
because it has more AP holders and less frantic visiting tourists. For many reasons, from better character interaction (less autograph books!), to a more relaxed atmosphere overall.
But I have seen some of the place holders, and I am sorry, I think most blanket layers are AP holders, mostly because most DL guests are AP holders. I was not saying most AP holders are spot holders. But I have read articles (Mouseplanet, MiceAge, etc) about this issue, and they even say there are
some sort of clubs that have special blankets dedicated to the practice (usually Fantasmic) of saving space. I think that was a Fantasmic thing only. Worse, there are local "tour guides" that hold the spaces for a price. Guests PAY for someone else to hold spots for them, which usually entails 1-2 people holding space for 6-8 or more "clients". I read about that, here on the DIS boards, with many DISers posting about how wonderful this service is. So some place holders are WORKING, lol, and I bet they have APs too.
And the average new guest out of towner would not even bring a blanket to a theme park. (they could use coats though) I do see lots of older guests, grandparents, holding down the spots at times. It is a fascinating phenomenon because it just never happens at WDW, where you have to hold your own spot or else, lol. You have to beg everyone around you to send 1-2 family members on a bathroom sprint.
That was a very good point about AP holders being able to see the show at any time, so why would they do this? It seems like some, and really it is a very small but determined # of guests out of tens of thousands, like to see Fantasmic, the Fireworks, parades over and over. (they are spectacular of course)
I only get to DL a few times a year, I will watch all these things from a distance and stay out of the fray.