I guess I just don't see how it adds to immersion. I suspected it was another suggestion to limit long rests, but your idea about making food sellable from vendors would make it more viable and present fewer issues. Ultimately though, if it wasn't implemented to serve a purpose other than "immersion" I'm not so sure it would feel like anything more than one additional chore. I'm not really against the idea, I just prefer that gameplay mechanics have a purpose other than "it's cool".
Isn't it the point of a game, to be "cool" ?^^
And yes, you're right, I think it will give me a reason not to rest too much, or even to greed a fight, for fear of losing too many resources. I find it thrilling !
