Cat food is food specifically formulated and designed for consumption by cats. As obligate carnivores, cats have specific requirements for their dietary nutrients, namely nutrients found only in meat or synthesised, such as taurine and Vitamin A.

Hey look, your Wikipedia link says the nutrients cats need from meat can be synthesised in literally the second sentence.

Vegetarian or vegan cat food has been available for many years, and is targeted primarily at vegan and vegetarian pet owners. While a small percentage of owners choose such a diet based on its perceived health benefits, the majority do so due to ethical concerns, such as about the large environmental impacts of animal agriculture.