Curious why rotary encoders aren't as good. I'm guessing because you cannot visually see the volume or the potential range based on the state of the interface? (E.g., How much is 1 tick of the rotary encoder? Who knows?)
I've been thinking about using a rotary encoder for lights to deal with this problem specifically (light state being out of sync with a fader/pot). I figure I'll just have software figure out the new state based on the user interaction.
Either not enough resolution to tweak some nuance or too many rotations needed for a wide swing. Perhaps rotaries with 256+ increments per rotation exist, but I think most are much lower. A sample I just checked seems to have 64 per turn, pleasantly surprised but still not really there yet. The 128 values of a legacy MIDI CC are typically over 270 degrees I think.