One of the interesting things about the cryptocurrency space is that it's challenging one of our fundamental assumptions about economics, namely that currency is a winner-take-all market and everything works better if there's a single currency used for everything. Instead we're seeing that currencies can actually have different properties, and that this can actually affect which currency you'd chose to use in which circumstance. Want to do things that you don't want the government to know about? Use a privacy coin like ZCash or Monero. Want to let your computer programs transact economically? Use a platform coin like Ethereum, EOS, or Tron, and select which based on whether you want to write your smart contracts in Solidity, WebAssembly, or Java, respectively. Want to define a marketplace and create a utility coin to mediate transactions in it? That's what coins like BAT (Brave), Kin (Kik) and now Libra (Facebook) do.

The primary functions of a currency (store of value, medium of exchange, and unit of account) are also now getting unbundled: Bitcoin is used as a store of value, but not as a medium of exchange, while something like Monero or BAT is much more a medium of exchange than a store of value, and stablecoins like Tether or USDC are filling the unit-of-account role. That trend has been going on for decades - stocks and bonds are stores of value, but not mediums of exchanges or units of account, while in-game currencies are units of accounts but not a good store of value or unit of exchange - but the crypto space has made it explicitly clear.