WHY Did YouTube Do Away with Stable Volume???

That honestly was one of the most useful features they ever introduced! I could actually hear videos clearly that I couldn't before because the audio was so low, even turning the volume on the video player and on my device all the way up wasn't enough, but having Stable Volume sure did fix that! Now it's gone. WTF?

Come to think of it, why is it always the actually useful features that YouTube always does away with? Anyone else remember the pop-out video player? You probably don't, because that didn't last long either, but that was great too: pop out a video into its own separate little window so you could keep browsing the internet and still leave the video playing in a separate window.