Etherdelta has been doing this for ERC20 tokens for some time: https://etherdelta.github.io/
Associating the ERC-20 protocol with the current mania and nonsense of cryptocurrencies doesn't seem fair. It's simply a method of creating a sub-currency, which yes is often unnecessary but marketing is a powerful force so it happens.
Having seen small rural communities try and fail to create their own local currency years ago it's only a matter of time before some try again digitally.