Have you ever wondered why gold have been and ceased to be money so many times in history? Many talk about returning to gold, but if gold was that much better than fiat money, then why has fiat money recurrently replaced it? The supporters of Bitcoin would say centralization is to blame, since it allows the manipulation of the monetary system in favor of the wealthy. However, since most gold monetary systems were also centralized, how could centralization explain fiat monetary systems, especially debt-based ones? Clearly, centralization is not enough to explain our current monetary system.
Gold wasn't lost as money because of "centralization." It was lost as money because governments desire the ability to debase the national currency for deficit spending.
Upon a gold standard, the ability of governments to spend beyond their taxable means is limited. Upon a fiat standard, the ability of governments to spend beyond their taxable means is far less limited, for they can merely print some portion of the deficit (and the public, taught in government schools their whole lives, never learns about the insidious inflation tax they endure).
Put simply - the gold standard tends to be abandoned by governments because it restricts their ability to spend. It limits their power, so they find ways and excuses to get rid of it.
Of course the motivation for debt money includes the "ability to spend," although this only hides a deeper motivation: the massive transfer of wealth resulting from a continuous creation of new money always born in the hands of the same few people.
Although it may seem that governments have an inherent desire for deficit spending, the gold standard was abandoned mostly during war periods, and those wars were motivated by private interests rather than by public ones.
The key point is that gold was the historical basis for fractional reserve banking, which in turn was the historical basis for central banking: gold makes no distinction between money itself (the actual equivalent of all possible equivalents) and its representation (the commodity, gold), so it not only allows but naturally favors and even requires fractional reserve banking (just remember how fractional reserve banking evolved from gold keeping).
Bitcoin, on the contrary, has the distinction between money as an abstraction (a private key) and its representation (the corresponding public key) as an essential, defining feature, which is as much an essential difference from gold as one can be.
