I'd argue that it would be binary, but not digital. It's not communicating a signal represented as a number - it's transmitting some level of power, which is available in two amplitudes (none and some). So it's analogue, binary (as opposed to continuous), but not digital.
A dimmer makes it continuous, so it would no longer be binary.
PWM, BPSK, etc. are similarly binary, but not necessarily digital. Few people consider a switch-mode power supply to be digitally controlled - it has continuous input, continuous output, and continuously-variable pulse width, yet the output pass device is only in one of two states - switched or unswitched.
Discrete != digital.