Some thru hikers are also backpackers, but thru hiking is not backpacking, IMO. Every book you read (well, the majority of them) you see them getting to the point where they are either all about miles, all about food, or all about finishing.... I read a recent freebie from Kindle, Gang of One, and the guy spent way more time meeting his wife in her camper than hiking and talking about the trail and scenery...

Another reason that if I ever do the PCT it will be a long series of section hikes over a number of years, and not a contiguous trip. I'm not a thru hiker.