markets is akin to asking whether the fall of ancient Greece proved
THE failure of democracy. (It didn't; there have been some decent
democracies since then.)
The error stems from a poorly phrased question. At most, this crisis
proves one failure of free markets, or maybe the complete failure of
one free market. Not all free markets are the same, just like all
democracies aren't. After all, our democracy doesn't decide whether
to go to war by popular vote, as the first democracy did :-).