Why does the concept of hybrids violate any ethics? What moral principle does it break?

Now I'm not saying that you have to like the animal or not, but I don't quite understand the deep hatred that I see for hybrids. (unless you're a car) I probably would not breed one, but I wouldn't have any problem with owning one in my collection. I do not have a problem with their existance either.

Also I don't think using the word sickness in a thread about snakes, is probably the best idea... but that may just be my old age kicking in.