Once upon a time there was a little boy who was so unfailingly cheerful his parents were actually worried. When his puppy died, he was glad, because now his puppy was in Heaven. His parents finally decided the kid needed serious reality therapy, so that Christmas, instead of toys, they arranged for a truckload of horse manure to be dumped in the yard. To their amazement, the kid let out a scream of joy, jumped in the pile, and began frantically digging in it with his bare hands. When his parents asked what he was so happy about, he replied: "With all this horse$### here, there has to be a pony somewhere!
There is no pony in blogosphere comments. There's only horse$###.
The sad story of the site PostSecret says it all. PostSecret allowed people to post secrets anonymously by phone. The flood of vileness caused the blog owners to remove the phone app.
It depends somewhat on the site, but in my experience, maybe 10% of blog comments are informed and useful, 50% or so are banal and the rest are abusive and ignorant. Even Scientific American and the New York Times are mostly flooded with banality.
So, if you have something intelligent to say about anything posted here, set up your own blog and have at it. And if you're anything else, nobody cares what you have to say.