True, it could work like pinboard or MetaFilter. In general, I doubt that the network effect can be overcome for consumer platforms. People want to share their

True, it could work like pinboard or MetaFilter. In general, I doubt that the network effect can be overcome for consumer platforms. People want to share their book reviews. Why should they limit themselves to people who pay? Paying only works for those who want social filtering. To compete with Goodreads, the data would have to be free like Wikipedia, for other competitors to emerge so that it is not just a village but a country with many villages. But then, it's a rtf reader situation where it is difficult to survive as an app creating company.