"percentage of the total torque that 'x' exerts on the crank is now 100 times smaller"
Yes, but it's still 'x'. It doesn't really matter what the % of total torque is. What matters is the difference in work required. The work required to rotate the crank one revolution on the stand is no different than the work required to rotate the crank one revolution on the road. Integrate that over a long ride and see how much extra work you have to do. To some people, that is worth the expense. To pro riders in a big stage race, that is certainly worth the expense, even if it is only in the kJ range.