Facebook does something productive, but I don’t see how stocks map to that productivity. The only way I really see to take a stock and have it represent actual value, is to plug it into the stock market. But this is just trading between those trading on the potential value of the stock -- not on the value it gives to them (that is, they don't actually want the stock for any purpose but to move it -- they're middlemen).
But if you imagined no stock market existed (you remove the middlemen), then is there any reason for anyone to want stock? That is, at the end of all this stock trading, who actually wants to have an FB stock? It doesn’t appear to me to be the public, or FB itself, or any particular investor. Everyone wants to hold stock, in order to get rid of it later (earning on the arbitrage) — but no one apparently wants it in the first place (it grants no power, potential earnings, and doesn’t really represent anything meaningful AFAICT); this is why the only thing to do with a crashed stock is to wipe your ass with it -- stocks are meaningless without their backing company -- but I'm currently not finding a way to claim that stocks are meaningful even when their company exists!
Currency could be said to be in the same boat, but at least till the gold standard died, at the end of the day USD could be said to be minimally wanted by the Feds — mapping to gold — producing that base value you could further justify trading and speculating on. I suppose I don’t understand what justifies a base value for USD post-gold standard either (it was bootstrapped, and now is self sufficient? Or perhaps because we all assume the feds will always a assign value to it)
Furthermore, because there’s no one who wants a stock in the end, there seems to be no reason for the value of a stock to rise/fall based on company successful — no more reason than my trash should.
AFAICT, its just a happens-to-be — by the powers of god, luck and collective will, stocks have arbitrarily been selected to move with company performance, despite there being no real relationship between the two (the only people who want it more are people who intend to sell it to others who want it more — but you follow the chain through and you can’t find anyone who wants it for any other reason).
And I really want to be convinced “a collective fiction” is not the answer (stocks exist because stocks hold value because stocks exist. Stock value tracks company success, because company success tracks stock value, because stock value tracks company success).