I just finished writing a mess of very complicated types that can parse an open API spec, provide the request types (body & params) as input, and restrict the return to the appropriate response type... I hooked this higher order function into our API and immediately found 30-40 different places where the implementation was not aligned with the spec.

The devs now have guardrails in place to make sure they follow the spec...

Advanced types are invaluable when you are writing a framework or library... But in every day implementation, I agree they should be used sparingly.

I have 7 years of ts experience and I'll still 'as any' a reduce function from time to time