Why do new socks come in "zip lock" type bags?

I’ve noticed that a lot of things come in (cheap, shoddy) zip lock type bags. You know, ones where you open them and both sides of the strip stay stuck to one side of the bag?

Anyway, I bought a new bag of socks the other day and they’re in a zip lock type bag. I don’t think they ever go bad, especially if you haven’t used them yet. They probably don’t need to be air tight.

My brother said it’s so you can put your old smelly socks in there for safe and odor-free disposal. But I’m wondering if there’s a real answer. Besides upping the already insane price of socks?