… As a result, when the cost structure for creating, say, an encyclopedia changes, our existing assumptions about encyclopedic value have to be re-examined, because current encyclopedic values are relative, not absolute. It is possible for low-cost, low-value systems to be better than high-cost, high-value systems in the view of the society adopting them. If the low-cost system can increase in value over time while remaining low cost, even better.

… Barriers to both access and re-use are built into the Britannica cost structure, and without those barriers, it will collapse. Nothing about the institution of Britannica has changed in the five years of Wikipedia’s existence, but in the current ecosystem, the 1768 model of creation – you pay us and we make an Encyclopedia – has been transformed from a valuable service to a set of self-perpetuating, use-crippling barriers.

… The measure of possible virtues of an encyclopedia now include free universal access and unlimited re-use. As a result, maintaining Britannica costs more in a world with Wikipedia than it did in a world without it.

Clay Shirky in Social Facts, Expertise, Citizendium, and Carr