[breischl]

>Is not the atomic indivisible of computing no more that a simple switch? A binary?

It is for the dominant computing paradigm currently in use, but that isn't a universal truth. As I understand it, we use binary logic primarily because it's more tractable for humans to think about and work with, not because it's the only option or even the best option in all cases. For instance there are plenty of analog computers in history, which are in some ways more closely related to biological "computers".

https://en.wikipedia.org/wiki/Analog_computer

[OkayPhysicist]

To my understanding, the main advantage of digital over analog logic in computing was (and probably still is) its resistance to small errors. Nonlinear components like transistors and vacuum tubes aren't exactly the most consistent parts, and factors like ambient temperature can make even otherwise linear parts a little wonky. The "on/off" paradigm gives you a lot of tolerance of deviations from the ideal. Storage is also a big factor: it's really hard to store analog values, whereas on/off is approximately trivial.