Just driving stepper motors and reading encoders (and a bit of maths to connect them). Teensy etc. would probably be too slow to do the step generation and encoder reading in software.

But to be honest you never want to do that in software (except on weird chips like XMOS ones). You'll almost always want to do things like that using hardware timers and counters.

The maths will be done in software but a Teensy would be fine for it.