[say-vagnes]

It's not about most errors being due to type mismatch, as much as it is about being able to model your domain.

By having types, you open the door to formally describing the building blocks of your system. This lets you create very specific, well understood, pure pieces that then are composed together to bring about your desired functionality.

Why rely on documentation that a compiler cannot statically verify, as opposed to a type (annotation or otherwise) that can?

I think you're correct regarding your "most errors are caused by" comment, and no programming paradigm will ever get rid of these - you can always find a way to write bad code. And you are also correct that there are type zealots out there who create beautiful prisons they call abstractions. But at the end of the day, types are a tool, and while I'd highly recommend learning them, I also recognize some projects and teams will never make use of them.