This is not the point of the article. Even at the level of the objects themselves, 1 : integer is not 1 : rational. The latter is an ordered pair (1, 1) of two coprime positive integers, or an equivalence class of ordered pairs up to cancelling. Some ugly hackery is required to really make the integers equal to their respective rationals, and its consequences aren't great either (just imagine that some rationals are pairs while others are not -- that's what you get if you forcibly replace the rational k/1 by the integer k), and no one wants to do that.
