Here's the number that should end the argument fast: a rust spot caught early is usually a $100-$200 fix — some hardware swaps, a little lubrication, maybe a cable replacement. Ignore it through another humid season and a hurricane-prone winter, and that same issue can turn into a full panel replacement or a spring failure that takes the whole door down with it. That's the real cost of "it's fine, it's just a little rust."