Why do people say that??? With a difference of 16 teeth between chainrings, a compact shifts about as poorly as a setup can while still being called marginally workable. All other things being equal, a system with 8-12 teeth between rings will shift much better than a compact.

Compared to a 30T granny ring, a compact gives up about 12% on its lowest gear. If you figure 5% per 'gear' that's over 2 gears you lose by going to a compact. If you never use less than third gear on a triple, and you never use your tallest gear either, then a compact makes sense for you. I use 'em all, though.