Clay makes the argument that large two-way communities become simple broadcast models.   I disagree.  Sure, it's true that nobody can handle input from a million sources, but nobody wants input from a million sources.  There is too much noise and too many off-topic contributions.  What I do need is the ability (degrees of freedom) to connect to any subset of those sources I desire.

Too much input is exactly the reason that discussion groups can't scale.  A serial thread on a topic with a million contributors swamps a discussion.  As a reader, I can't find the good posts in massive discussion group or mailing list.  The signal to noise ratio is much too low. 

However, weblogs change the equation.  Each contributor gets a space where they can express their ideas.  Their contributions aren't buried under the weight of the community's contributions in their personal space.  The central hub of a weblog community provides a way to find these personal spaces, with each personal space acting as a filter or proxy for thousands of other sources.  As the community scales the number of potential connections balloons.  It isn't a broadcast system with one source of content, it is decentralized system with millions of sources.  It is a marketplace for ideas and insight.  By subscribing to a particular weblog, I am opting to transact with their idea flow without the noise of other voices. 

So, rather than subscribe to all the potential contributors to a community, I can subscribe to as many good sources (people with minds I trust) of insight and information as my time will allow.  The difference between this and the broadcast model is that the content I get isn't all from a single small number of sources, it is from a multiplicity of sources from within each of the communities I belong to.  I can create my own trust network without having it thrust upon me.  My ability to post the information and insight I acquire from this network, adding my own views to the mix, to my own weblog enables people to use me as part of their trusted network of content suppliers.  I become a filter that leverages their time.  The flow I send back to my source (through an annotated post) allows me to provide feedback to that person.  They can either reply or not, depending on how much they value my opinion.

What Clay is grappling with in his analysis is the difference between active spaces (conversational) and passive spaces (broadcast).  The extremes on either end are instant messaging and webcasts (or simple static Web sites).  Weblogs combine the best aspects of both active and passive systems.  I can post items that are essentially a conversation with one person or I can publish an item that is read by millions of readers.  On a graph of scalability vs. community, simple IM would be in the lower left hand quadrant.  Webcasts, and static Web sites, would lower right hand quadrant (high on scalability and low on community).  Discussion groups would be in the upper left hand quadrant (high on community and low on scalability).  Weblog communities would be in the upper right hand quadrant (high on both scales). [John Robb's Radio Weblog]
2:04:38 PM    comment