You could only use my argument that way if you had some justification for what happened in 1970, and why the market failed to sort things out for millennia. My claim is that what happened was "vocal proponents [...] with a strong smell of moral superiority" made it happen in basically the same way that women finally got the vote. That is to say, market efficiency is a relatively weak and gradual force, not something that proves that all current social structures are perfectly optimal.