Why does Safari not enable YouTube 4K by default?

Safari does not allow streaming YouTube videos in 4K by default, why is this? Chrome is such a resource hog that I have shifted over to Safari as my default browser. With the new tab groups Safari is even better.

You can enable YouTube 4K in Safari by enabling 2 experimental features.

Go to Safari > Preferences > Advanced > and check Show develop menu

Then go to Develop (top menu) > Experimental Features > and enable:

• • VP9 SW decoder on battery
  • WebRTC VP9 profile 2 codec

VP9 is an open and royalty-free video coding format developed by Google.

MBP Late 2013 • BigSur 11.6 • Safari 15.0