A Eurorack system can show much of its causality in the physical domain. Wires, knobs, and sliders create a Rube Goldberg legibility. With the modules, they create a notation.
Plugging, turning, and sliding a Eurorack system is a way of writing music. Writing the first draft on a Eurorack is slow. Editing is not because there are no incidental abstraction layers. That's the appeal of it to me, I think.
My current system has few abstraction layers. There are digital abstractions at the front end; a Qunexus and an SQ64 for input and there's digital recording at the back end. But there's no black box in the middle. The modules are all analog.
Nothing with a screen. Nothing with menus. Just wires, knobs and sliders. Just observable causality.