How Airbnb Smoothly Upgrades React
medium.com
medium.com
Which means most of this massive body of work has been invested solely to prevent code rot. It's a sad state of things.
it seems that software has taken on the marketing of hardware. just like we've come to expect a "new" iphone every year, we expect a new framework version every year, regardless of any major improvements that justify the effort.
i get how the microservice/microfront-end architecture makes these updates painful so you want to be mindful of not getting too far behind LTSs but i think being on the latest version just to be on it has become pure bragging rights for most tech companies.