I do like the idea of lifting the burden of rewarding the social part from the base layer. It would get rid of a lot of issues and points of friction.
Communities are already working well for creating, following and moderating content. But when we look at Steem Engine tribes, we could see that most coins went on a steady downward trend. That was to expected but it calls into question as to what extend SMTs will be able to achieve the rewarding part. There are lessons learned with respect to inflation, initial distribution and even if every community needs their own token or if there could be groups of communities working with the same SMT.
An ideal solution to me would be that a casual user doesn't even come into contact with HIVE and only encounters the SMTs of their communities. Trading of RCs should be handled by app- and community owners and moderators.