You think Shopify should've written their backend in Rust? I really wonder if people saying this have ever used Rust.

Ruby is great for developers of all skill to learn and be productive.

Rust is fast as the devil but you have to be a damn good coder to learn it. Even then I doubt you can be as productive managing memory all the damn time. It's a low-level language great at low-level things.

Ruby is a great option for Shopify. Rust is a great option for Firefox's Servo (though that project failed so maybe not).

cost of improving the language vs cost of hiring new people in different language, keep things stagnating for 10 years while rewrite is in progress, having to deal with talent exodus etc.