In my experience there is a MASSIVE difference in the type of feedback someone gives on code vs a design. A design doc encourages "why" questions to get everyon

In my experience there is a MASSIVE difference in the type of feedback someone gives on code vs a design. A design doc encourages "why" questions to get everyone thinking about the problem space. For example, a design doc comment might be "why are we suggesting a Rust Webserver when nobody in the company is proficient in Rust yet?". In my experience those more subtle questions are much harder to raise once a prototype is working - "why does the team's experience matter? look how great it works! If you don't block it we could get this to production in a week by just polishing the prototype!"