In part, these numbers reflect Google’s dominance in web search–41/61 is a whopping 67%, which is within epsilon of Google’s reported share of the web search market. But the larger point is that most sites depend on web search for the majority of their traffic, which makes search engine optimization (SEO) a matter of life or death for commercial sites in general, but especiallty online retailers, publishers.
So it’s not surprising that SEO is a multi-billion dollar industry, comparable in size with the pay-per-click (PPC) advertising industry. And, to the extent that the SEO industry is helping to organize the world’s information, it’s earning its keep. But it’s hard to know how much SEO improves the efficiency of the information market vs. how much simply fuels an arms race.