NEW HAVEN, Connecticut — China’s efforts to rebalance its economy have been an abject failure. Nearly two decades after former premier Wen Jiabao bemoaned the Chinese economy’s excessive dependence on investment- and export-led growth, the problem has gone from bad to worse. The lack of meaningful consumer-led rebalancing implies increased reliance on these time-worn sources of economic activity, raising critical questions for China and the rest of the world.