I once wondered how the rust compiler was also written in rust. Seemed like a chicken and egg problem.

But once you write the first rust compiler in C, then you can use that compiler to create a second compiler in rust.

I guess once the chain exists, and we all know how to use it, it's only natural to stick the whitepaper onto it as it's founding document. Like displaying architectural plans for a building inside it when it's done. It's a cool practice.