Your blacklisting idea makes sense to me on the face of it. The list would be constantly growing but I suppose it would be easy to write a program for users that auto-muted accounts as they were added to the blacklist.

Initially I saw Steemit as having great potential for freelance journalism, but some time soon governments are going to wake up to the existence of the platform and have a fit when they realize they can't censor it. One scenario I can imagine happening is governments (or powerful individuals) start secretly putting large amounts of money into influencing what's going on on the platform. Say you are a journalist who exposes government corruption, quickly you find that there is no opportunity for you to make money on Steemit as they are heavily downvoting.