Anyone (including Steemit) is able to develop changes to the Steem blockchain code. Once it is developed, it is up to the witnesses to decide whether it is adopted. Right now Steemit is largely defining the development path for the blockchain, as their developers are doing a vast majority of the development. It would be great to see more changes from community developers being proposed, developed, and accepted by the witness.
As far as SMTs, there has been a lot of conversation about them with the top level witnesses, and although there hasn’t been any official decisions made as far as whether to accept or reject the proposal, the general consensus seems to be that the idea is supported.
Thank you!!!