Sure, but because of the transistor’s nonlinearity (cutoff and saturation regions, for mosfet at least), we get digital logic. Digital logic means that errors don’t accumulate, and that prevents complexity from infecting everything in the computer. We can put neat little abstraction boxes around parts of the SoC, and then do the same with our software.

Digital computers are only noisy compared to the simplest processes, like a low rate transmission line. Compared to biological or chemical processes, a digital computer is just ludicrously low-noise, because noise doesn’t propagate unless there is a major fault.