Sound management is a nightmare... you put some playlist on Music and start to surf the web with Safari only for the music to be interrupted because whatever random web site has a video on auto-play... Seriously?
On Reddit as you need your finger to scroll and a lot of videos are in the way it's almost impossible to scroll without touching one-> the music will stop.
I’m not saying sound management doesn’t suck on iOS. It does. But the scenario you describe is forbidden by Safari and Chrome on mobile and desktop. Unless I’m misunderstanding something.