EVERYBODY knows that smaller frames are lighter and stiffer.
So if you want a light stiff bike, it makes perfect sense to start with as small a frame as you can find, then munge it to fit by hanging long, heavy, flexible cantilevered contact-point attachments off it
My next race bike is going to be built around a 12"er kiddy bike, with a really long seatpost and stem. And with the training wheels removed to save weight. Those things are sooooo stiff... great for power transfer.
who doesn't have a last race bike to upgrade to a next race bike