Cause it's my (our) blog, my (our) discretion.
If you're racist, sexist, assholish, repetitive, annoying or even just plain boring - I reserve the right to edit your comments and replace them with the Barney song
I love you
You love Me
We're a happy family
Or maybe I'm a little teacup. It's a mood thing really. Also possible are such nursery hits like The Ensy Weensy Spider or Humpty Dumpty.
I also may turn really awful comments into a blogpost to be made fun of and mocked accordingly. If you don't like these policies you are free to write your own blog and you are free to write on your own blog how mean and horrible I am and how you're just a poor misunderstood asswipe. But not here.