I have been running the game for a couple of weeks, and in my current route I load a previous save once or twice (depending on what I accomplish when on the run) to save time / reset my position in the map.

I saw reloading a save to refresh the map utilized in a (if I remember correctly) pretty outdated run that I found when starting to run the game, and began using it myself.

Could anyone tell me a bit more about why this rule is in place?

Mostly to just prevent someone from loading into a premade save that has more stuff completed.