Are you saying that cats don't have a devastating impact on wildlife? They're by far Europe's most widespread predator. This is an article about the impact of certain farming techniques on wild bird populations, if you'd like to read studies about the impact cats have on wild birds and other small wildlife, I (or google, for that matter) can provide you with hours and hours of fascinating reading material.
Here's a sample of some cat-related facts:
A recent study in the UK, for example, showed an estimated 9 million cats, 38 times more than the fox population. Those 9 million cats kill an estimated 92 million small animals, including 29 million birds and 5 million reptiles and amphibians. Cats are responsible for the extinction of 33 species of birds. There's absolutely nothing natural about this many predators roaming around, killing things needlessly and spreading disease unchecked.