I think you are mixing the idea of BEAM robotics (why that, I prefer to not use this term), with analog electronics.
Analog circuits are in major applications more fast than a micro processed one, that have a clock to process instructions. The "problem" with analogs is in part with noise, but early computers are made analog, operational amplifiers are made to do computation with analog circuits.
The 74LS series, have a bunch of digital discrete ICs, they are not microprocessors, but can be flip-flops of some types, bus drivers, gate logic, and can do
a lot of "processing", again generally faster than a microprocessor.
But, today digital electronics and micro-controller or processors reached a point where cost is acceptable even for the hobbyist. Sometimes is more easy to make a software than the equivalent analog circuit if possible. There a number of reasons.
But you can see that micro-controllers still have analog circuits for the user, like analog comparators, A/D and D/A converters, and much more depending on the application, so majority of circuits are mixed type
But Software-less robots, spacecrafts etc. might never be close to feasible. Right?
That is really application and project dependent, and at some degree opinion based.
Op amps for example with an analog encoder, could close a PID loop, very fast ones.
But the signal to the PID would come from a software and a D/A. So I don't say its impossible, but there's no subject to go this way, but again, they are in major projects mixed circuits, not only digital