It affects everything

Even those who acknowledge that our treatment of animals is indeed a great evil may feel that it is, like the other evils in our world, simply a product of human limitations, such as ignorance, pride, selfishness, fear, and so forth.

According to this view, the horror we inflict on animals is a problem, but not a fundamental cause of our problems—and, because it’s a problem for animals, who are less important than us humans, it’s a lesser problem.