I think that's totally backwards. A good type system _improves_ iteration speed, it doesn't slow you down. When I refactor a Rust program, I have very high confidence that if it compiles, I haven't accidentally introduced a bug.
I don't write much Go code, but my company does. I have seen so many incidents and bugs whose root cause was: someone changed a library, that broke the semantics that users were relying on, but everything still compiled fine, so nobody noticed the subtly wrong behavior for a long time. An incredible amount of money has been lost like this.
Go simply does not give you the tools to prevent these issues in the type system, you have to rely on really thorough unit tests (which inevitably don't get written in the spirit of "moving fast".)
I don't write much Go code, but my company does. I have seen so many incidents and bugs whose root cause was: someone changed a library, that broke the semantics that users were relying on, but everything still compiled fine, so nobody noticed the subtly wrong behavior for a long time. An incredible amount of money has been lost like this.
Go simply does not give you the tools to prevent these issues in the type system, you have to rely on really thorough unit tests (which inevitably don't get written in the spirit of "moving fast".)