The transition to CSS transitions seems primitive to me. https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Animati... makes it sound very much like a fire-and-forget approach.

My concern, also when building UI with React, is that web design is often only interested in end-state of an interface, playing a bunch of fire-and-forget animations to transition between states.

The reality, that only games and Apple seem to have embraced, is that it's far more sophisticated for animation to reflect a state that can change at 60 or even 120 frames per second, depending on what the user is doing.

This is a great presentation from Apple, Designing Fluid Interfaces, that captures the concept: https://developer.apple.com/videos/play/wwdc2018/803/

Am curious: have any web frameworks embraced this approach?