Actually it is. Just depends on the person. Considering humanity sucks, these types of people are RARE.
Misanthropy doesn't mean you're against having friends. You just really don't like human kind in general.
Humanity in general. It's like I can't assume every tattooed person is bad. There are some people who aren't bad seeds.
There is no purpose of misanthropy. Misanthropy is simply the condition of disliking or even hating humankind in general. There is no purpose to it. So no, it doesn't defeat the purpose. :')