After using this keyboard, I can't imagine ever buying another keyboard without a knob. It's really great to control your audio volume with an appropriate hardware control rather than pressing the same key 15 times in a row like an idiot or fiddling around with the mouse.
You can configure the knob (or any key) to do different things with different key combinations, at the hardware level even (with the Via tool), so you don't have to configure multiple OSes one-by-one to do the same thing. I've configured Alt+Knob rotation to control my screen brightness, which I adjust multiple times per day. You can also configure it to control the zoom, or move the mouse, etc.
The knob also functions as an additional key if you press it downwards. I think by default it is configured to mute (which makes sense, since by default a knob rotation without any other key combination controls the audio volume).
When you go look for keyboards with a knob you won't find many, and the Keychron keyboards (Q-series and Q Pro-series, the latter being both wired and wireless), are really the best there is AFAIK (unless you create your own, perhaps).