What I have read about raw feeding is that a cat's digestive tract is intended for raw eating, it is much shorter than a human digestive tract and this is why the bad stuff passes through quickly.
I don't know anything about whether kibble stays in the digestive tract longer or differently (seems a strange thing IMO) but kibble at best is a bunch of stuff that's been cooked so much and at such high temperatures that it no longer is what it is. What the bunch of stuff is can also be lots of chemicals, and at the very least they finish it all off by spraying it with chemicals that make it "palatable."
http://truthaboutpetfood2.com/pet-food-flavor
http://www.popsci.com/science/article/2013-03/chemistry-kibble?single-page-view=true
"Pyrophosphates have been described to me as “cat crack.” Coat some kibble with it, and the pet food manufacturer can make up for a whole host of gustatory shortcomings. Rawson has three kinds of pyrophosphates in her office. They’re in plain, brown glass bottles, vaguely sinister in their anonymity. I have asked to try some, which, I think, has won me some points. Sodium acid pyrophosphate, known affectionately as SAPP, is part of the founding patent for AFB, yet almost no one who works for the company has ever asked to taste it. Rawson finds this odd. I do, too, although I also accept the possibility that other people would find the two of us odd."