> In other words, the economic surplus did not go exclusively or primarily to the richest.

That was in large part due of strong leftist movements and states that forced the capitalists to share the increasing wealth. WW2 and the resulting labor shortage and other special circumstances contributed as well. Currently no such movements and circumstances exist. Globalization and the resulting free movent of capital has put capitalists in a better position to direct the extra wealth for themselves than ever before. A global movement is required to get a meaningful share of the increased surplus to the workers now, and that is very hard to do. The market will not do it on its own, as the demand for human labor eventually decreases due to automation.