[Blackthorn]

You can generate perfect band-limited sawtooth waves at 44.1khz, there are multiple techniques for doing this and most production digital synthesizers use them.

Oversampling gives you headroom for aliases for the rest of the synth that is more vulnerable to it.

[evo]

Yeah, I was oversimplifying a blit, the raw waveforms are usually okay, but I distinctly remember old-school VSTs where you couldn't achieve a nice saw lead at 44.1.

[Blackthorn]

It's tough to tell without specific names, but I imagine a lot of particularly old* VSTs were written to use naive sawtooths rather than perfect band-limited ones, which would have terrible aliasing at 44.1 khz. Oversampling those would help a lot!

* Some people are still making this mistake, despite information on the (many) ways to do it the right way being widely and freely available!

[evo]

I wonder if there's also distortion or ring modulation stages where some of the energy above hearing range might spill into audible sidebands if they're not nyquist-limited first.

[Blackthorn]

Yeah, that's the "rest of the synth" part that's more vulnerable to aliasing.

There's some ways to do band-limited distortion but...they aren't nearly as widespread, easy, or universal as band-limited oscillators.

Ring modulation is funny though because you'd ideally want the sidebands to modulate down by default rather than filter them out, that's why you're using it.