In hindsight I believe it's because we were following the startup mythology of "building a solution for the problem that you have" a little too closely. We failed to realize that this is really a problem that only small startup teams (usually a group of founders) have, as they need to keep in constant sync. It doesn't really scale past that. As soon as you have any sort of mixture of roles, personalities, or start to grow the team this is a communication method that just inherently doesn't scale well.
I do believe there is something here for small groups of founders/friends though, good luck!