Probably because kibble is so dry and compact. It will change and expand a bit in the gut once eaten. Table scraps and raw...well they kind of are what they are. I feed everything but when I feed kibble it's usually not more than 1.5 cups at a time. I have heard of dogs bloating (and dying) that were only raw fed so I think there is possibly a genetic component as well.
Liesje & the K9s
Nikon (GSD) U-CH SG Alta-Tollhaus Bono SchH1 KKL T1 FO PA TF-III FDCh-S CL1-R UJJ U-CA HIT TT CGC
Coke (All-American) VPC's Coca-Cola CGC, couch warmer extraordinaire
Indy (All-American) Blue Horizon's Indigo Girl, flyball star in training
Rainbow Bridge Kenya (GSD) U-CH Alta-Tollhaus-Krieger Lamb Chop CL1-R CL1-F RA HIT TDI TT CGC
vom Blauen Horizont / Blue Horizon GSDs