Comment by crazygringo

Yes and no.

Clearly there is a need to give different volumes to different apps, so you can have quiet background music while a timer app is louder, or Zoom is louder.

Ideally there would be an OS-level mixer to independently set the volume of each app. I believe Windows has this, Mac definitely doesn't. And for convenience, an app's local volume control would exist, but set it at the OS mixer level, so you don't have them competing with each other.

But without this, an app does have to have local volume controls.

Also, it's important to be able to set gain as well, i.e. turn the volume "above 100%". For those YouTube videos that for some reason are only 5% as loud as other videos. Even better is if you can set the gain per-video so that it won't be absurdly loud and clipping when you move on to the next video.

Bonus points if an OS or media player ever gives the option of a dynamic compressor, so you can actually listen to those amateur podcasts where one speaker's microphone is 10x quieter than another's. Or listen to the quiet parts of classical music recordings even in the presence of background noise.