It's a combination of things imo....it was already mentioned but CF has a cult like fan base, just like a lot of other things people are passionate about. When a outsider doesn't understand it becomes annoying.
I've done crossfit for years and I was serious about it. I even attempted to make the cf games for a while, but you rarely hear me talk about it.
I view Crossfit as something similar to mma. It introduces you to a lot of different styles that when a specialist sees it they are like wtf because it isn't their norm
If I've never done crossfit I would've never been into Olympic weightlifting, gymnastics, off road biking, etc...