Why wouldnt you blog about it?

Since I have begun blogging myself, Ive become much more interested in the blogs of others. AND SOME OF THEM have been through some real interesting stuff in their lives but choose to write about everything but that. I just dont get it. Writing is a way to let go of harbored feelings- I place to free your fears- a place to be heard in full. SO Why wouldnt you blog about it?