What Does Slack CTO Cal Henderson Tell Startups to Optimize for First?

On GeekWire, Slack CTO Cal Henderson says that for almost any software company that is not already a giant, the first job is finding product-market fit quickly. Slack was not designed on day one for more than 10 million daily users. The first version put in people's hands was the wrong one, and the early years were spent learning which parts of a tool that worked for small engineering teams would work for everyone else. He warns that building for massive scale before that fit is addictive for an engineer and a way to get stuck. Cloud hosting is what made the fast loop possible. At Flickr, he says, they bought servers and racked them themselves.