[wat10000]

I said "tend to," not "guarantee."

You'd expect this to happen with a couple of reasonable assumptions, like stock prices being somewhat based on real value most of the time, no wide-scale long-term economic collapse, and new companies replacing incumbents over many years rather than very quickly. If the real value of a company stays constant, then the stock price should, on average over the long term, rise at a pace that matches inflation.