Again, this was back in kde 3 days, where desktop usage was more prominent than laptop, and even on laptop, a mouse with a scroll wheel was still a common accessory since touchpad gesture wasn't really a thing yet.

> Knobs are great in the physical world, never met one on a screen that wasn’t hard to use.

Well, I just gave you a perfect example where a knob on the screen was immensely useful. Of course it will be silly to try copying the physical world as-is, but with a little bit of creativity, applied in the right context, a knob on the screen can absolutely be useful.