[kinjba11]

It's in their FAQ.

> Why not develop Mojo in the open from the beginning?

> Mojo is a big project and has several architectural differences from previous languages. We believe a tight-knit group of engineers with a common vision can move faster than a community effort. This development approach is also well-established from other projects that are now open source (such as LLVM, Clang, Swift, MLIR, etc.).

https://docs.modular.com/mojo/faq.html#why-not-develop-mojo-...