That and unless if you pay alot of money or spend a bunch of time with training, dog barking is very loud and disrupts neighbors which can be a big inconvenience. Plus food will cost quite a lot if you have a big dog. Unless if your dog is small and isn't that active, food will cost a lot
I'm not saying that everyone should like cats and cats only, I'm just saying that they are a good pet for an owner who doesn't have a lot of money or time, and is a more quiet or calm pet too (depending on the cat)