This is incorrect. Zoom doesn't use webrtc audio and video channels, only data channels, and has reimplemeted audio and video channels on top of that, doing the decoding in js and probably wasm.

They also limit the resolution to 480p for the web app, probably because of performances. Browsers and zoom both use h264, but browsers usually use vp8 instead.

There is no reason webrtc cannot offer the same quality (or better) than zoom, at the same bit rate, but it all comes down to the actual implementation of browsers and web apps. webrtc-based apps work well, these days.

Thanks for the information, I also realized that a while after writing the comment. No wonder the experience is worse than in their native client, data channels are still terribly unoptimized (sometimes even broken in some aspects).

Edit: https://bloggeek.me/when-will-zoom-use-webrtc/