What the advice misses is that even at an early stage, you need decisions in place that allow scaling. For example, if you buy 1 truck for your one-person shipping company, you can move 1 container at a time. Adding a second truck lets you move 2 containers. 37signals is smart--they built their software so that it could grow to 2 servers--but they left that out of their advice. There must be a path from simple to complex.