There are plenty of members that want to remove PoB from the STEEM currency and make its minting separate of any "reward pool" related to content. The problem is that different communities care about different types of content and should not have an impact on other communities.
SMTs can't solve this problem if STEEM remains PoB. This is because the STEEM currency will always be viewed as the "real" asset in the system unless it was made neutral by separating STEEM minting from the reward systems.