This is a logical, well-thought out argument that I largely agree with. The one thing I wonder is if, as brand advertising is increasingly transferred to the internet and those dollars are spent on sites like Facebook, we see overall spending drop and an increase in spender (and consumer) surplus to the detriment of the middlemen. The analogous example is Craigslist -- a site that destroyed millions (billions?) of advertising revenue and that will likely never be recovered but was overall a net gain for consumers and advertisers both in a way that is hard to quantify.