There's a joke that CrossFit is like reverse fight club: the first rule of CrossFit is that you ALWAYS talk about CrossFit.
There is a corollary to this is, which is that if you don't like CrossFit, you ALWAYS talk about how much you hate CrossFit.
While both behaviors can be irritating, I'll give the CrossFit lovers this: at least they're talking about something positive. Yes, you may want them to shut up already, but at least they are trying to add something positive to the world. The haters are adding nothing.
I wonder what it is about our society (or the Internet) that causes people to want to spend their free time crapping on other people's activities. Seriously. Of all the things you can think of to do with your free time, you want to use it talking about why other people suck? Why not make a positive contribution to the world instead?
You think CrossFit is a terrible fitness program? Fine. Share the one you think is better.
This applies for a lot of things, not just CrossFit. You don't like a particular martial art? Great. Share one you think is better. You don't like a particular diet? Great. Share one you think is better.
Add something useful to the world, not just more negative drivel.
Alternatively, just get off the keyboard and go train. Stop worrying about what other people are doing with their time, because in the end, it doesn't affect you anyway.