Originally Posted by
spinnaker
Extremely poor advice. Very unhealthy for you feet. You need a stiff sole to help prevent flexing of your foot. A stiffer sole aid in power transfer too. Mountain bike shoes are even probably stretching it a bit on sole stiffness but they are a satisfactory compromise.
What's bad about flexing your foot? In particular: what's unhealthy about it? I've had a few aches and pains from riding a bicycle, but I can't say that I've ever finished a day with aching feet.