Data.Set function mapSetMonotonic consider harmful...?

In Data.Set the function mapSetMonotonic is defined as a straightforward function that maps a function over the elements in the set:

mapSetMonotonic :: !(a -> b) !(Set a) -> Set b
mapSetMonotonic _ Tip = Tip
mapSetMonotonic f (Bin n x l r) = Bin n (f x) (mapSetMonotonic f l) (mapSetMonotonic f r)

However, this easily violates the ordering property of the resulting set, for instance use mapSetMonotonic (~). Is this function actually used? Shouldn't it be removed, or at least be documented with a warning?