When the problem space is less well defined the type-related boiler plate adds a lot of friction. It's not impossible to overcome that friction but it slows down progress. When you're under a tight deadline development velocity is often more valuable than absolute correctness or even overall runtime efficiency.

An delivered product that works is usually more valuable than an undelivered product that's more "correct" or efficient. A development project is just a cost (for various values of cost) until it ships.