Have you not read the post? Because compile times. Rust has awful compile times. If it didn't, I'm sure the Roc team would have stayed with Rust.
I don't understand why the goal is not to (eventually) implement Roc in Roc, maybe with a dash of something else for the "platform".
Roc is pitched as a general purpose functional programming language with great performance.
How does a compiler not fall under this category?
I first learned about Roc from this talk:
https://www.youtube.com/watch?v=vzfy4EKwG_Y
That's a niche that is not currently filled (well, maybe MLTon) and that has me very excited! I'm sure I'm not alone here.