That can be said about the operating system you're using.
Well, let's see. Most of the market share of operating systems is held in Windows and Mac, then a smaller share in Linux. Windows is the only one of the three that provides standard volume control on a per-process basis. One out of three is not standard. Then let's look at essential: in this case essential refers to being crucial to its existence and usability. Since it's the responsibility of the process to control itself, not the Operating System's to control it, I wouldn't consider per-process volume control essential to an operating system either.
So, pretty much, you're just wrong.