> > just from a common-sense POV, if I'm prototyping a project, looking for product-market fit, the last thing I want to care about is that my typeability is recursively enumerable or what-have-you.

Then don't. It's not like Haskell forces you to, that's a myth about Haskell. You can get away with strings and integers everywhere if you so fancy.

There is just no common-sense in thinking that computer assisted programming is slower than unassisted.