The Steem blockchain is already a decentralized exchange. steemit.com/market
Right now the only two things traded on there are STEEM and SBD. With the intro of SMT, since all new tokens created with that protocol are paired with STEEM, they will be traded (I presume) on the exchange also.
But I do agree with you...this is another overlooked point by most. As the banksters send their government cronies out, we will see the increased usage of decentralized exchanges...Steem is already in that market.