It reduces complexity and uncertainty. At the company I work for we have 2 internal APIs being worked on: 1) A freebase/metaweb style API backed onto a relati

It reduces complexity and uncertainty. At the company I work for we have 2 internal APIs being worked on: 1) A freebase/metaweb style API backed onto a relational database 2) A traditional set of web services backed onto a document based database The former gives us the ability to invent the questions we want to answer and validate whether those are valuable questions. But it carries the risk of complexity and the problems of scaling in return. The latter gives incredible performance once you know what questions you want to answer. But it is much harder to prototype things on as that's a bullet-proof big industrial thing and things move slowly in there. We basically recognise a difference in the balancing of pros and cons between the systems that help you prototype fast and the systems that help you scale dramatically and securely and that have to be maintained. And it sounds like this is the underlying point about using a framework for prototyping and then building your own simple, pared down specific thing.