Tokens have it much easier than actual coins to find platform to directly sell crypto from person to person, kind of a perverse incentive
Coins have to bribe a centralized exchange, difficult to have a decentralized and independent platform.
The bitshares guys claimed somewhere in forum that everyone can run a gateway for free. This would allow to deposit/withdraw any coin and trade it against all currencies in the system, Bts, bitUSD, Btc, Eth etc have all some volume
Or swapbot, they also claim that swapbot is open source and everyone can run their own version of swapbot. But this one wasn't made for trading, more like for "selling to the public".