Absolutely. Pets are nice, but they are a lot of work. I love the idea of having cats and birds and lizards and fish, but I can also understand that not everyone has the time/patience/effort to dedicate to such a thing. Sometimes life is busy, and if you don't have time or energy to dedicate to an animal companion, you're better off not having them.
There's also the matter of the short lifespan of most pets. I'm actually not too fond of getting attached to something over the course of 10+ years and one day just having it gone, either run away, dead from illness, or otherwise. I could probably go the rest of my life without a pet simply because I don't want to deal with that kind of grief.