I completely agree with Gatorpit. Its the reason that there are millions of homeless cats and dogs in shelters worldwide and are killed. People buy a cat, it grows up or it meows excessively and people dump it. They get a new cat, it grows up or it meows excessively, that one is dumped. Its a vicious cycle.
When you get a pet, it is a lifelong commitment that you take on. Cats are LIVING CREATURES, not interactive toys that can be disposed of when they aren't wanted anymore.
That, and they don't neuter them...unless a cat or dog is top-shelf show material, it should be fixed. Waaaayyyy too many "oops" situations out there. You may keep your animal in your yard but that doesn't mean the neighborhood wanderer can't get over the fence. And you might want your animal, but those not-quite-carbon-copies of it might not be wanted by anyone else.
I have four female barn kittens that I got from another barn and they are all slated to be spayed as soon as they are of an age where it an be done. Yes, I am going to spend the money to spay BARN cats. I care enough about the cats that I don't want them to become kitten vending machines and I don't want to overrun my neck of the woods with feral cats that will continue to populate or become coyote bait. They are here to do a job, which they are doing quite well, and I am rewarding them by taking proper care of them....giving them food to supplement their mousing duties, vaccinating them, worming them and fixing them when that time comes. The world would be a happier place if others would do similar.