Back when I began blogging with Jim Craig over at Ipse Bogit, I allowed for unmoderated, anonymous comments. That proved to be unwise, and we began forcing people to have a registered Google ID and moderating the comments as they came in. Alan Lange from Y'all Politics praised me on that decision, as did others. There was, of course, great hue and cry from those whose purpose in commenting was not to debate, but rather to abuse and defame. Like the poor, it appears that the demented will always be with us.
I continued that practice when I took over Cottonmouth a year ago. It has proven to be a solid method of creating a healthy atmosphere of debate. Comments from folks like Bill Billingsley help move the debate along and are very much appreciated. Of course, I still retain the unfettered right to reject comments before they are posted. And I will reject your posts and keep you from posting going forward if you engage in behavior that is defamatory or abusive, online or off.
As Alan Lange put it in his response to the above-linked Ipse Blogit article, a person's blog "ain't no democracy." Bottom line: Newspapers don't run every crackpot's letter to the editor, and blogs don't have to allow all comments.