Yes, of course. But the automatization of this process (you pay today with your SDB because I am sure they will arrive in 3 days) means that you have to wait 3 days, then exchange them for STEEM, then exchange STEEM for fiat value or other crypto unless you don'have a STEEM-100%backed system.
This means that you have to do 2 trades SBD --> STEEM; STEEM --> SOMETHING ELSE that creates more devaluation risks for users. You have two operations that are a source of risks, not only one.
Also considering that waiting 3 days in a so volatile world like SDB market is very dangerous, even more than wait for the average Crypto transaction.
This doesn't mean that I am bearish about this project, but in my opinion SP is not money and SBD is even more dangerous for sellers than Bitcoin or STEEM. Because you have greater devaluation risks (another trade to exchange SDB in STEEM and, before of this, 3 days to wait).
This problem could be at least in part solved by creating a free market for SDB similar to STEEM or other crypto markets, with crosses to FIAT or other crypto...