Yep I agree that architecture plays the largest part. But I really don't think it's about a language being boring vs not! Pure functions are easier to reason

Yep I agree that architecture plays the largest part. But I really don't think it's about a language being boring vs not! Pure functions are easier to reason about. So it makes sense that a language that encourages their use will be easier to reason about - which will help with maintainability. Same goes for concurrency patterns - the closer they are to the language, the less room for mistakes. I think the same for testing, but a lot of the time it's up a layer of the stack with a framework.