Biz Stone and Evan Williams were on stage at TechCrunch Disrupt to talk about their new publishing platform, Medium and, of course, their cleverly named company Obvious Corp (obviously).

And they also talked Twitter for a bit. They discussed their lack of a business model for a good stretch of time, and they also touched on THE topic among Twitter developers: Twitter’s API.

Though they didn’t take the bait when asked if their new platform, Medium, had “quadrants” to share (referring to Twitter’s new developer guidance separating applications in to four quadrants or categories), TechCrunch reports that Williams dig delve into Twitter’s API issues a bit (very little bit):

Maybe the most interesting statement of the session came from Evan Williams, though, who noted that Obvious is taking things slow with its API. An API, he said, needs to have a purpose, and developers have to be really conscious about what they want to do with an API. “We didn’t have that all figured out with Twitter,” Williams candidly noted.

Well, that would be an understatement to many developers. Thanks to Twitter’s pending API changes, it seems a new app is closing up shop every other day.

Here’s the full “fireside chat” to hear more:

(TechCrunch Disrupt image from TechCrunch)