It benefits users in the short term that get paid in SBD. Listing on Binance would only improve the price of SBD. It would also benefit Binance since much of the Steemit users need to sell SBD to buy Steem. Only listing Steem defeats that purpose. Some of the other exchanges still have Steem and SBD, but don't have functioning wallets which makes exchanging SBD/STEEM impossible. We need more options. Eventually down the road, SBD is intended to be used as a pegged dollar. If it is everywhere like Tether is, then it may actually be a replacement for Tether. Imagine that! The more exchanges, the better for Steem and Steemit community. Listing on Binance is a big step and will make the currency more mainstream.