My friend and  noted author Alan Dean Foster bunged this one over to me, and I couldn't  in a million years put it as well.  So much so, that I want to pass it  on.
 
Quoted in Maureen Dowd's column from todays NY Times: 
Leon  Wieseltier, literary editor of The New Republic, recalled that when he  started his online book review he forbade comments, wary of high-tech  sociopaths.
“I’m  not interested in having the sewer appear on my site,” he said. “Why  would I engage with people digitally whom I would never engage with  actually? Why does the technology exonerate the kind of foul expression  that you would not tolerate anywhere else?”
Why must the common denominator be so common?