It's true that code is knowledge, but I think it's talking more about not having slightly different versions of that knowledge floating around the same code bas

It's true that code is knowledge, but I think it's talking more about not having slightly different versions of that knowledge floating around the same code base. For example, if there is one canonical way to do something, such as adding a table row and having to remember to update counts somewhere else, then that should be done in one place. That way, if that agreed-upon way changes you don't have to remember that it's done in 25 other places across your code base.