>A humanoid robot takes roughly 5,000 steps per hour. Each step sends a shock of 2–3× body weight through the leg actuators—forces that would be fine occasionally, but become destructive when repeated thousands of times without pause.

As someone who comes from the world of running and knee problems, I feel this misses the issue. Normal walking should not produce these kinds of shocks unless your gait is really jumpy or otherwise screwed up. You only start to see these forces when running and that's where technique becomes important even for humans if you want to prevent damage to your joints over long distances. But at least for walking I suppose that a fully articulated humanoid with all the degrees of freedom of human gait should be mostly a control problem, not a mechanical engineering one.