It's funny, before I knew about React (this was ~2014), I wrote a ~7ksloc webapp with jquery and underscore that also just used memory for state and triggered a re-render of things when inputs changed. I haven't dug into how React works at a deep level lately, but at the time, for my relatively simple thing (basically did a few pivot tables worth of calculations for some financial stuff), it wasn't really that complex. I'm sure that enough engineers working on a framework for a decade can make it very complex, just wondering, as I do with many mature pieces of software, if a ground-up rewrite based on the same concept but knowing what they all know now would look drastically different from the latest dev build.
