Earlier quoted context omitted.
None of what you're saying is wrong, but remember the context here when using the historical performance of markets to talk about these kinds of hard-and-fast rules. The period for which we have market data also spans: the period with the fastest growth in global population, including population growth in developed markets; the outbreak of extended peace between world powers; and roughly tracks human exploitation of…
If things are bad enough that the 30-year treasury outperforms global stocks at maturity, then the correct hedge is canned food, guns, and ammunition. The most pessimistic long-term outlooks cannot be mitigated by any sort of market mechanism because that level of pessimism implies a breakdown of the market itself.
And in part it's precisely because of the worst case scenario happens where worldwide stocks don't outperform treasury bonds, you're likely living in a world where your money isn't legal tender anymore anyway, and any stock/bond investment decision you ever made basically irrelevant.
So if decisions regarding the extreme downside risk are irrelevant, you might as well optimize for the upside.