Why are so many people giving their cats food they shouldn't have?

While I understand giving your baby the occasional treat, I'm appalled at the number of people here who regularly give their cats rice, wheat, or corn based food, or vegetable or dairy. When was the last time any of you saw a lion on the Discovery Channel who was munching on a root?? Cats eat MEAT and nothing else...they are pure carnivore and need the Taurine in meat to live. Filling them with the rest of aforementioned garbage will only lead to long-term health problems. Am I right or what??