To explain, when ned wrote that Steemit is centralised and Steem is decentralised, he meant (i presume) that Steem is run on webservers around the world run by witnesses who are a group that is populated by anyone who wants to be in it, whereas Steemit is a website that is run by a corporation that just uses the decentralised database/blockchain of Steem. I don't see anything wrong with that in and of itself and it doesn't inhibit the decentralised nature of the blockchain. The problems come when Steemit is the main interface to Steem from the public's perception and when the features on Steemit subtly nudge Steem away from decentralisation in practice and towards centralisation due to a conglomeration of power.