Pet food companies will tell you that the industry is tightly regulated and that your pet's health is being fastidiously protected. The FDA can't even keep up with human food and didn't lift a finger on behalf of the pet owners during the ethoxyquin debate. The American Association of Feed Control Officials. The fox guards the rabbit hutch here. Almost all manufacturers use stool hardening agents in pet food.
Convenience again triumphs over pet health.
Stool modifiers make clean up easier and mask the effects of nutrient malabsorption. It's easier to just stack those little bricks into a pile or kick them elsewhere. Consider however the strain on your pet's innards. Well, they do all that and more for your beloved pet. The explanation for including these usually is that they are fiber sources for your pet's well being.