My mind blown experience was listening to a Rich Hickey talk (maybe not [1]) that flipped upside down my accepted method of thinking about types and type system paradigms. I still love writing Haskell and Rust, but I see the warts that he is so concisely pointing out. The either type really sticks out to me now, and I see the problems with overtyping what are essentially maps, and how rigid that makes every aspect of your programs. Currently I deal with a fairly large go monolith that had some clean code practices in it, and changing a single field that is going to make it into the public API ends up being hundreds or thousands of lines of changes. Such a waste of time to CRUD what is a map of strings.
1. https://youtu.be/YR5WdGrpoug?si=jRsXcYlwRuz0C1IN