What this article tells me is to not share data with foursquare since their priority is to sell that data and make money and not to help me make decisions on where should I be eating.
Well to get you to share your data, they need to provide value to you which is helping you make decisions on where to eat... that's the web business model, you give up data in exchange for something, company sells data (and sometimes access to you too, like Facebook).
I don't see how you learning this changes anything. Either they were useful to you before or they weren't. What does it matter how high on their priority list it is? If you were their number one priority but they weren't helpful would you use them?
They're using your aggregate data to reward companies that you like and punish companies you dislike. It will make companies react to peoples preferences faster and provide a better product.
Of they would just track me, without any other features, it would still be a win.
But that priority doesn't influence the quality of the recommendations they make. The data they sell doesn't influence the places they tell you to visit because that would in effect bias the quality of the data.
