How is it that a single person named Edwin Brady can think of, implement and have a programming language with a decidable type system that is more complex than Swift, working on it part-time?

I'm sorry, I consider a company worth a trillion dollars, sitting on billions of dollars it doesn't know what to spend on, that spends billions per year on R&D, to know the basic properties of the type system their most actively developed programming language uses.

That's just me.