[the8bit]

Each ad serve is not worth that much to start with, facebooks CPMs are about $7-8, so they are getting $0.007 per serve with extensive targeting. The falloff is something around 10x+ for completely non targeted ads which for most sites push them below the level of economic feasibility.

This is also why if you stumble into some parts of the web, they vomit out a billion ads per page to try and compensate.

Really the problem is that there is a tremendous gap between the costs to serve content and users willingness to pay (either directly or via any indirect method). It is a tremendously deep hole we've built with freemium models that will probably require some level of societal agreement to dig back out of.