I think your surprise is justified, especially since you've been in this world for a while. But I think there is an apparent (but not real) contradiction between offering designs for free so people can go and build something themselves, and then charging money for R&D. This is what is meant by the term trade secret.
re: Woodworkers and co -- sometimes. Room & Board doesn't share their designs. Tartine Manufactory probably has a cookbook.
> You're reading into the comment an emotion that did not exist when the message was sent. If you read hostility, then that's no what I was trying to infer.
I'm genuinely really happy that this is not the intent. Challenging phrases and Socratic questioning can really come off as hostile.
