I feel like if it were actually an order of magnitude less complex, it would be eminently obvious from a blog post about it? Maybe I'm just tired and don't "see it" for whatever reason, or maybe I need to find some better examples.

From the moment I saw a post about immer.js, I was sold because it seemed like an obviously better solution for the vast majority of cases where I would otherwise grab Immutable.js, a library that I wanted to like but inevitably struggled against.

This.. isn't quite as revelatory. I'm not saying it's not all that you claim it is, it's just that from a glance, I don't see how this somewhat different approach addresses the problems I run into often with React in a major way (beyond the claimed performance boost).