How do you mean that this causes 'nightmarish complexity'? I guess it's true if you measure the amount of complexity that powers the framework, but the visible API's, the resulting project structure and the implementation itself is incredibly simple and versatile.

I'd say it's one of my favorite properties of component frameworks as opposed to raw element modification, templating solutions or classical MVC.

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.