you need proprietary code to playback bought/rented movies from eg. Youtube though

Agree, google done got us good with widevine DRM. Time for another go at standardized open-source DRM implementation?

The average user doesn't want a web browser with only basic features, they want all of the web to work, all of the time (excepting maybe ads.)

There are always extensions, that currently follow standards and work on all major browsers with minimal changes.