Sorry for replying to this old thread …
One thing that surprises me is that in that era relative encoders were used extensively, also for audio related stuff like volume and EQ. That has so many advantages, especially currently where you can change parameters from different sources like iPad screen. Looks like these were abandoned again for some reason. If someone understands why, I’m very curious about this.
I can only think of a few differences. Cost, feel and centre detent.
I seem to remember there being a slight increase in cost if you wanted to buy encoders, but there wasn’t a lot in it. Good pots tend to have a nice resistance to them and feel smoother than the step up/down notion of the encoder. The centre detent on a mixer, some people love it, some people don’t.
Personally, I prefer a pot for a mixer control and an encoder for anything else like a looping function. That’s their intended use - to replace switches, although they can easily be mapped to simulate an analogue pot.
I suspect cost and reliability were key factors. High-quality, endless, push-encoders are definitely more expensive than potentiometers. They are more complex with additional failure modes.
Plus you need extra LED ring indicators for position feedback which also adds cost and complexity.
