That said, a webcam can only do so much even with proper lightning and a clean background. They're never going to be as sharp, or as bright, as a nice fast lens on a quality camera.
If you've got decent lighting, that's not true.
My Logitech C920 -- the most popular webcam of all time -- outputs a fully sharp 1080p. With normal front lighting, it handles 30 fps perfectly without visible noise, i.e. full brightness. There's zero quality difference versus using my DSLR. It's as sharp and as bright.
Now sure it can't do low-light conditions well or do 4K or depth of field or a fisheye lens or the other million things a DSLR can do... but for videoconferencing purposes it's literally indistinguishable in quality.
I'm sorry but you're just incorrect here. It might be minimal at Zoom resolution but it's absolutely there.
The sensor size, the resolution, the aperture, the optics -- they're all sufficient. There's nothing to improve upon that will yield a measureable difference. There's no distortion, no chromatic abberation, no noise with decent lighting, nothing.
Everything you're talking about matters if you're dealing with low light, or zooming in, or you want depth of field, or 60fps, etc etc etc.
But what precise detail do you claim is better at 1080p with the DSLR? Because from your list, it's not resolution. You don't want a larger aperture because you don't want depth of field on videoconferencing. And "quality optics" means nothing -- if there's already no distortion, no blurring and no aberration at 1080p, then there's no more quality to be found.
It's just the physics of photography and sensors. Photographic equipment is designed around thresholds of quality. If your equipment is already above the threshold you need, even better equipment makes zero difference.