The Oil Drum

Yes, but it isn't black and white. Even for energy efficiency, there are degrees of mechanization which enhance human productivity with very little resource consumption when compared with their use. Windmills to pump water, drills to get water, make holes in wood, saws, etc. Simple machinery can be more efficient than hand labor alone. The target resource consumption vs. future usefulness is what I refer to as Net Creativity. The most useful way I know to determine sustainability of a particular machine is whether or not the resources to build it can be made/obtained within a reasonable time and distance/transportation constraint, such as within 6 months and within a national border.
Animal power is often a poor substitute for machines. You don't have to feed the machines when they aren't being used. The ox doesn't work as hard as a horse, but can be milked most of the year. Humans are notoriously unreliable, especially if entertained and infatuated with machines. Proper application of machinery to enhance human ergonomics is something we have learned through overmechanization that can be very effectively applied to Descent Planning.