What you are suggesting then, a non-comparable browser experience, already exists and has for years, yet to no avail. You would get niche technologists and die hard enthusiasts only and the rest of the world would trudge happily into the future, DRM and net nutrality distant memories.
What you and I want, what HN and friends want, is not even a debate most realise is happening let alone that it affects them and will affect them profoundly in the future.
The masses are deciding what our internet will look like for they comandeered it years ago.
The great thing about the open web that you rightly mention is still kicking, is that it's full of places and services that are driven by humans and passionate communities. Nothing about EME stops those communities existing, but nothing about those communities is going to stop Netflix being the most popular platform and using EME/DRM.
If you will excuse my fluffy analogy, the web is a farmers market that has a shopping mall being built right next door. What I think would help the web, is educating people that it's better to go to the farmers market so that we can support entrepreneurial and local community endeavors rather than stuffing corporate coffers and enabling that consolidation.
The support for different versions that does exist in browsers tends to be minute: ripping out support for older versions would cut out almost no code, because there's basically nothing specifically handling them. (Heck, the only forks in CSS are for quirks and limited quirks mode, and both of them affect very, very little of the layout engine.)