Steemit is not a currency. Steemit is not the crypto-platform. It is only a website that interfaces with the blockchain. It is the mount Gox equivalent of bitcoin.
Yes, you can create a room full of bloggers just like you can create a pool of bitcoin miners. This would the create an unbalanced centralized currency right? Why hasn't this been the case for other cryptocurrencies such as bitcoin? Visa could swoop in and own 99% of all of the bitcoins and then tell everyone you can only use bitcoin through Visa. This could happen, but then they would be buying a useless currency. If I invest in it with the intent of creating instability through breaking the principles of the currency then I will destroy the value I put into the currency which will mean I will be paying to see it's demise.
I was actually thinking about having pools of posters earlier today to increase small cuts of the pull and dull the large cuts. This could happen just like it does with other cryptocurrencies and mining. But the more crap someone posts or spews the less we will see it and the less profitable it is. If they spew create content and deserve to be up voted. It would mean someone is better at sharing their opinion than I am and will reduce my cut of the great content pie. But if there is great content from bloggers, then huge news outlets could perhaps use steemit as a source in their posts. Which would mean we would be given a lot of views and our steem would go up in value.