I've thought this myself before. My rationalization is that most of the commenters are also regular readers - probably disproportionately regular, as they retu

I've thought this myself before. My rationalization is that most of the commenters are also regular readers - probably disproportionately regular, as they return to read replies to their comments - and so generate a disproportionately large numbers of page views. The sites are scared to turn them off lest the commenters stop returning, hurting ad revenue. Would be nice to hear from anyone who can confirm or deny this hypothesis.