The only people who are saying that remote desktop is the only remoting method supported in Wayland instead of remote windows are totally, utterly, wrong. And have never even tried it. Actually, I think it's the other way around: I'm not sure remote desktop is really supported at all, bar kludges like remoting a new compositor.
The references to VNC and RDP were about the conceptual differences between sending a stream of rendering commands, and sending the pixel buffers. That's all, nothing else. I'm not referring to reimplementing VNC or RDP exactly 100% like-for-like with all its bugs and deficiencies, because why would we do that?