I wonder if convenience has something to do with it.
I don't know about anyone else, but I have to spend hours and hours preparing ALL my meals from scratch. AAAND, you can't really eat primal food out-of-hand. Look at all of Mark's recipes -- they are all real sit-down saucy meals that you have to put on a plate and use a fork and spoon, usually eaten during a defined meal time. It's not easy to eat this way if you're constantly chafeurring kids or running errands. That's why convenience food was invented.
Sometimes I really miss the days of being able to just grab something at the checkout or dip into a box of Triscuits in from the of the TV. Doesn't seem to matter if it's carby or not. I'd be eating bags of macadamias or beef jerky if it didn't cost so dang much.
5'0" female, 44 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 111 on sugar cheat. Currently fighting off sugar/candy cravings with bulletproof cocoa and a little rice.
I (try to) follow by-the-book primal as advocated by Mark Sisson, except for whey powder and a bit of cream. I advocate a two-month strict adjustment for newbies. But everybody is different and should tweak Primal to their own needs.