Facebook is learning that what people like to chat about when they should be working isn't a very effective way to match ads to eyeballs. LinkedIn on the other hand has a very specific type of advertising structure, and one that works very well: job postings. Is there an ad people want to see more than one promising a better career?
I bought Google in its early days because I figured out the business model, and that it was simply a ubiquitous newspaper with a gargantuan circulation that would make billions by selling ads around its content. But I didn't buy Facebook because I have never understood it. But here's another angle that bothered me.