9. Western conspiracy. Chocolate is universally addictive and desirable, so Western firms are depriving Chinese of chocolate for a reason, one correspondent suggested, I think in jest: "If we withhold chocolate long enough, they're sure to forgive our debt."
Thanks to all readers for their responses. On my last day in Beijing, in a little convenience store a stone's throw from Tiananmen Square, I found a slightly dusty Dove dark chocolate bar.