Well the problem with the gold standard as of today would be that there simply isn't enough gold. You'd have a very deflationary environment. This is fine for cryptos as an isolated ecosystem. But it would likely be very bad for the world economy in it's current state. In a deflationary environment, incentives to spend are dampened (up to the point of being removed). Thus, spending decreases? Not bad you might say, but keep in mind this also means that corporations will not invest, or hire new workers, because sales plummet. Also, see here: https://en.wikipedia.org/wiki/Gold_standard#Disadvantages
In short: In a gold standard the rich become richer, while the poor (debtors) become poorer faster.