Gold is backed by being gold. It also isn't a currency anymore; the properties necessary to be a currency are no longer true of it. Wire me some gold, please. Not some numbers that are actually disguised dollars, some actual gold.

I'm not a goldbug precisely because I don't think gold is worth anywhere near what people think it is. The "durable value" it had in the decoration field is gone. If it were ever actually put to the test it would collapse to a much lower value reflecting its actual industrial and decorative values which are nothing like what they used to be.

The subjectivity of value is why backing is so important if your currency isn't to collapse. Something's got to stop the subjective system from just deciding the value is 0, aka, hyperinflation. Or, more accurately, realizing the value is zero.

It's easy to wave some academic theories around and act intellectually superior, but call me when you've actually got a functional currency that corresponds to what you claim is possible and even remotely resembles the real world market size of even Microsoft Points or Eve Online's currency. BitCoin is not it, and it won't ever be it.