There is indeed "scant evidence that disembodied talk can measure up to standards of deliberative democracy", but blogs as a technology are far more disembodied than alternatives such as wikis which have at least the potential for stable discourse and creation of factions around some views, rational or not. Rather than requiring a specific mode of argument and imposing a priori filters, the inherent respect of wikis for the reader's time, makes it possible to support stable terse structures like issue/position/argument that may persist for decades. It's this shift of time scale and choice of media, not the participants, that ultimately matters. See McLuhan and Korzybski on that. The hero-worship of "A-list bloggers" on the other hand simply fragments the conversation further with rewards for fragmenting, rather than for seeking consensus.