IRL? huh?

Have I walked into an alternate universe in the blog world?  I know I'm brand new at all this but I really don't understand what a "Mommy Blogger" or "Mom Blog" means?  Is that some sort of official title you get by joining some club or group or does it just mean any mom with a blog?  I'm beginning to see that there are cliques/sororities/associations online that are well organized and (in some cases) very controlling.  Isn't the point of having a blog being able to have your OWN say about things?  I just don't get it, but I never was the sorority type of girl.  I sure as hell wasn't going to have someone bossing me around just so I could be allowed (dripping with sarcasm) to be their friend.  And I LOVE (note the saracasm here too) when people write "IRL" such as "I've met her IRL" as though there is a seperation between the blog world and in real life.  I thought that's what blogs were supposed to be--an extension of our thoughts and ideas and just whatever we want to write about--isn't that real life?  Shouldn't everything that you put on your blog be IRL if it's the truth?