Lets have a look see at why people run blogs.
Primarily, if logic is any consideration, its so other people will read them - with all the happy psychological social status things that go with that.
Otherwise, it just dont make any sense.
But, unless we arent just talking about forcing your mother and defenseless grandpa to read it - who and how many people who read it becomes important. Theres a limited number of people who read blogs - just like any other good. The scarcity here is non-infinite time of the readers. (Of course it gets more complex, any particular blog appeals to a sub-set of readers only and since blogs have a negligible profit motive, the blogger will write more about topics that interest himself rather than pandering to the readers interest)
For whatever topic you are interested in, there are other bloggers out there writing in a similar vein. So the glorious battle for readership begins. And then, as is the tendency, the bloggers who cannot sustain a readers attention, whether through bad writing styles or unattractive topics vis-a-vis his competition will receive less reinforcement - aka fewer readers, less reason to have a blog.
Speaking for myself, even getting two comments on my blog was a happy moment. The idea of someone Ive never met, will never know and who will never know me, being intrigued by my writings is a real ego booster.
To draw a parallel with economics, blogging is not a zero-sum game. The amount of social prestige (or whatever term you prefer) isnt just shifted away from other sources. There is a greater level of it overall (though there are still losers and winners relatively). I'll explain -
Before we had mostly one-to-one communication - Telephones are a good example. Then technology gave us One to many communications - The Mass-Media. Now even more advanced technology has given us many-to-many communications - You read my blog, I can read yours too.
Under the One-to-many system, the prestige was one way. The pundit on TV was the pundit on TV. Period.
Under the Many-to-Many system, the pundit is the blogger but the commentator can expound the bloggers points, add to them, and perhaps convince other commentators or readers to check out his views on other topics - in essence become a pundit himself (even in the eyes of the original pundit).
Just goes to show that Economics, as Thomas Sowell says, is a way of thinking rather than a body of knowledge.
 There will of course be some pandering, but in the Mainstream Media the currency gain from pandering is not that limited - more money is always better. But in blogging the gain is measured psychologically - and people (bloggers) can get their psychological kicks elsewhere.
 John Walker of fourmilab.ch has a long article on this somewhere on his site.