Agreed. Moreover, certain "why"s like "why's this here instead of over in this class?" or "why is this bit of code repeated?" can't necessarily be explained by

Agreed. Moreover, certain "why"s like "why's this here instead of over in this class?" or "why is this bit of code repeated?" can't necessarily be explained by refactoring. And sometimes there's just certain technical limits you just can't get around, and you have to comment those.