Why are "Anonymous" comments reliably worthless?

Q: Why are "Anonymous" comments reliably worthless? 

A: Because of their provenance...

That is to say; Anonymous comments are worthless because of the kind of people who comment Anonymously. 

Which is why this blog is set-up to delete Anonymous comments unread. 

Example: Just yesterday I noticed that there was an Anonymous comment in the deleted files of my blog  - intended for a short post, which I ended by writing: 

"If you want to comment (but not anonymously!)"

Furthermore, at the top of the sidebar of this blog, the first paragraph opens with the statement, or warning: 
"Anonymous comments are deleted without being read."  

On top of which, as part of the actual form used for submitting each specific comment for moderation, is the phrase: 
"Comments are moderated. "Anonymous" comments are deleted without being read."

Just think about it - someone who commented Anonymously on yesterday's post had to ignore three statements Not to comment Anonymously - two of which made clear that to do so was futile.  
Consider that despite All This, someone commented Anonymously. 
This example says a great deal about the people (or entities) which comment Anonymously; and why it is that Anonymous comments are deleted without being read.