It seems like most of the complaints about craigslist (including those in the article) are ultimately complaints about what it's like to buy stuff from a random person in your area. People are messy, arbitrary and annoying if you don't know them and you only want to buy something from them. People are part of all sorts of social groups with all sorts of standards of behavior.

The dream of creating an app that can shield a person from all the uncertainty of buying from an individual is appealing - but I don't see how you could really offer a better deal. The problem is that however smoothly you put two people in touch, those two people will have to do lots of annoying work coming to an agreement and it's hard to see a lot saved by this initial increased smoothness. Oh, and if you filter out the annoying people, you filter out a lot of people who actually have stuff to sell too.