> In theory, there is no reason it can't scale indefinitely using something similar to IP.

I'm sorry, that just wrong. Gupta-Kumar capacity scaling law (2000) says that as you add participants, each participant gets less bandwidth, until it becomes impractical. Imagine a room with 10 people talking in it. Easy. Now imagine 10,000. Hard to have a conversation if it's still all ad-hoc.

You have to increase the width of the mesh.