From beauty.
Yes no one mentioned the octave until now.
It’s all about the harmonics sum.
If a square is an octave lower with odd only harmonics ,stacked with a saw 1 Oct up ,the harmonics stack becomes even - as an example. So its doings these sort of math, aswell as detune etc I believe.
I‘m watching MV videos at the moment haha
Not a lot of videos show off how nasty it can get.
Not that this does entirely (no high od on output), but it gives an idea.
Detuning for thicker sounds. Detuning for differently voiced sounds (5ths, 7ths). Cross-osc modulation if the synth supports it (ring mod, fm).
If you have the choice between one oscillator or multiple oscillators in a monosynth… I think the choice is pretty clear and the reasons become very apparent once you’ve used one even for 5 minutes. Go go multiple oscillators!!! One is cool, two is cooler, three is cooler-er. It’s not necessarily the most important part of the sound but definitely increases flexibility!!!
Thank you everyone for the insights.