While it’s absolutely true that baking is a strict formula, I don’t agree that not reaching a given temperature means it’s necessarily doomed. It might achieve a somewhat different outcome, but for a whole bunch of baked goods a lower or higher temperature with adjusted time will produce something perfectly acceptable.

As you say, most people have no idea what temperature their oven actually produces, or fail to adjust for the strength of fan assist or placement in the oven. Sometimes this leads to frustration and failure, but many delicious cookies have been baked with imprecission.