Unfortunately when the few control the whole, it's not decentralized. Not truly, anyway.
Is it social media? Both yes and no! It's a mix of many different platforms, but not fully any of them.
Steemit is a new online culture that has great promise, but only time will tell if it becomes a good example.
Right now it's sliding down a slippery slope and must be cleaned up. If not, there are many new idea's that can easily replace it.