Consider a 53/39 with a 12/27 cassette. The 39/27 ratio is almost exactly the same as the 30/21 ratio on a triple. How often do you use the 30/23 or 30/25? The jumps between gears might be slightly larger than on a triple, but there's also the advantage in shifting smoothness and accuracy.
Double/triple arguments are really about choices. Riding a double doesn't mean you have to sacrifice low gears as much as one might think...
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