They miss out how not-square the "square wave" is for a start. Its pulsewidth varies wildly across the compass.
I think you're right. We have a `pwm(hz,width)`[0] but I didn't try it. Was more focused on the ramp/sawtooth. Can't decide which one sounds better.
Always the square for classic acid house - the saw is better for more modern (and worse ;-) distorted acid techno