There are definitely areas of the browser API that are quite problematic, especially when it comes to things needed in a UI like Spotify and Slack use. A brief look into the drag and drop implementations in browsers should be illuminating enough.

The desire to use new features as soon as possible is driver enough I feel. Imagine having to wait years for parity between 6 different operating systems before being able to use classes, a language feature introduced years ago and that still isn't fully supported today.