Descentralization is a tool that helps with censorship resistence (that is the real goal). But some applications require some level of centralization that is inevitable. People don't need to run a full node to transact on bitcoin (and it would be impractical), they can do it just the same using a light wallet. The same principal applies when interacting with the steem blockchain. You can either run a full node and connect an interface to your local instance or you can use a light client (like steemit, busy, partiko, etc).