In my experience even things which are explicitly prototypes can be dangerous, as it can appear to be in the short term interest of the business to take a prototype and modify it as little as possible to get it shipped. I've seen this result in massive headaches and thousands of wasted man hours, and for what? Shipping an "MVP" that can't be effectively iterated on 2 weeks sooner? The worst case of this I saw, the technical aspects of this were bad enough that it was (in my opinion) what caused the product to fail.