Check out the pro peloton gear (not crits on flat terrain). Many of 'em are using mid to long cage RDs now. It ain't the 1950s-'60s with 13-21 or, at most, 24T big cogs. Best way to accommodate those 32T or larger cogs is a rear derailleur with a longer cage.
That said, a couple of my road bikes have short cage RDs (Ultegra on one, Dura Ace on the other) and they handle up to 28T big cogs, no problems. Especially with the 39T or 38T small chainrings. I have a couple of older long cage RDs intended for 1990s mountain bikes and have tried 'em on one road bike. No problem, worked fine. It's a bit heavy, tho', an older Deore LX with steel cage. I don't recall anyone I rode with mentioning this particular abomination. They were probably distracted by the magnificently bright purple frame with atrocious brownish-gold logos on my old Trek 5900 OCLV.