Why?

If you've been reading here recently, you will know that I like sewing and knitting............BUT, when browsing both sewing and knitting patterns I have to doubt the sanity of some pet owners.
Why? I hear you ask.
Simple, I do not understand why people dress up their pets. At first I thought it was just dogs, but when browsing for a suitable example to show you, I also found this , and now I know there are certifiable pet owners out there. There must be, as a big pattern manufacturer would not print and make available for sale such patterns otherwise.
BUT.....what I don't understand is why do people dress up their pets? Both my dogs do have coats, but I tend to only use them if it is raining heavily and the dogs have been clipped, or turns very cold very suddenly. They don't wear coats at other times, as ..in light rain, dogs periodically shake, which frees the rain from their coats and prevents it sinking through to the skin. [I hate it when people stroke wet dogs, as this breaks down their natural barrier and then the rain soaks through. Also, dogs coats get thicker if the weather gets progressively colder, so they are warm enough, without a coat.
The second example I found, well, all I can think is either the cat is very old and infirm, or it is stuffed. dressing a cat up like that would be pretty dangerous for your average moggie that likes to explore.
Ah well! It takes alsorts!