/diy/ - Do It Yourself

I'm playing with high power RF transmitters.
I have this application note reference design. The RF amplifier (the DRF1200) is driven by a 13.56 MHz clock signal with a specific pulse width, generated by the crystal oscillator and D flip flop.

Given that it's just a PWM signal, what's stopping me from replacing that subcircuit with a microcontroller? A microcontroller would allow me to implement a feedback loop for adaptive PWM to always have the optimal pulse width, and all kinds of other things to boot. Something tells me though, that if it WAS the correct/better way to do it, the circuit designer would have went with a microcontroller to begin with.
so in your guys' wisdom, would this be a viable alternative?