It's a fun tech demo, egui isn't meant to make websites. It's primarily for integration into games/other real-time-3D-rendered applications, and secondarily for GUI applications via eframe.

But I agree, I think they would be better served by making a normal website and linking to the demo prominently (For comparison, see iced's website https://iced.rs, which is great IMO)

It doesn't even load if you don't have WebGL2.