A world with cats is a world with billions of dead birds and small mammals.
Without them we will have even more insects.
So this time cats won’t protect us from diseases by killing the carrier, these time they help the carriers
Wouldn’t we have less insects because of increased bird, rodent and spider growth?
They still kill carriers for other stuff. Pick your poison, I guess.
Or killing them in the US will allow bird populations to recover, leading to birds killing more insects. Cats are not native to the Americas.