Ultimately, any user of any app built on the API has to be a user of Flickr as well. It also just introduces for a company at our stage a lot of headaches and risks, in that people are, excuse me, but shitty coders; they're not responsible in their use of the API or they write buggy code that hammers us. And that's happened a couple times. People can hammer you in other ways: they can scrape you, but they can hammer you a lot harder if you're exposing methods to the things that are most database- or CPU-intensive.