The problem with the lack of exchanges for HBD is that not everybody can use the existing ones. Both require KYC and on Upbit you need to be a korean national or use the branch for Indonesia. Bittrex is a USA exchange that has very stringent requirements to use. So most users are unable to trade them directly for BTC. Either they use a third party like blocktrades which carries an additional cost in fees or they exchange for Hive and then sell that on another exchange.