Witnesses can not enact any changes that are not implemented and released by Steemit.
To me this is one of the core issues that slows down innovation on Steemit.com. Two years ago it was sufficient for a witness to have knowledge about servers and how to run and maintain a node. The Witness rewards back than were a few 100 Dollars I think which covered the sever costs and a bit extra.
Today however that same model isn't sufficient anymore in my opinion. I don't want to get off topic but we can learn a lot from EOS here in a way that BlockProducers (witnesses) are expected to contribute to the development of the platform beside running a server and producing blocks.
The same requirement should be true here on Steemit and all 21 top witnesses should have the ability or hire the resources to suggest and implement improvements to the Steemit platform.
Unfortunately we can't count on Steemit.Inc to solve all issues for us, that is why the top witnesses should be empowered to make improvements them self.