I think you'll find that many frameworks actually emerged from a bottom-up approach. Build a web app from scratch, branch it and transform it into another web a

I think you'll find that many frameworks actually emerged from a bottom-up approach. Build a web app from scratch, branch it and transform it into another web app, then repeat until you get pissed off with maintaining all those separate code bases. Then, separate out the shared bits and you've organically grown yourself a framework. It's just usually the authors don't expose a clean API for all the steps in between.