It's annoying that Apple doesn't implement DDC control alright (neither volume nor brightness). I'm just trying to be helpful and point to solutions that I use daily for these use cases, not making a case, barely pointing out that things claimed to be impossible are not (and not argumentatively, only because folks may stop at that and have to endure something when there are solutions that would fit their use case)
Imagine having to install kernel extensions just to adjust the volume over a digital output like HDMI, maddening since you know it can do it, but stock MacOS won't allow you to. Or how about volume levels by app?