You still need a way to implement work, monitor that the work was done and be able to seize tokens if the work was not met. Can't imagine anyone wants to deal with the hassle on either side of the equation. NOW, if you implemented it as a backend mining of cryptonote token....that would be a more efficient proof of work.
With the benefit of hindsight that would have been the way to start the game back in 2014, but it probably took Steem to show the wisdom of why. Yes, if risto had launched a cryptonote token with plenty of warning, and that became the game currency of CK then probably no need to worry about these issues today. Problem is rebooting CK like that today doesn't help the bagholders, but it makes sense!