That is not literally a contradiction.
Not literally. It's possinle that the Marauders stole some other thing, and repurposed it into the Map.
But honestly, James Potter, Remus Lupin, Sirius Black and Peter Pettigrew were none of them great wizards, especially in their teens, so the less their involvement in the Map's creation, the more plausible I find the theory.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 116.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)