Everything is for sale, including a stake in Steemit. The difference here is that every user has the power to earn more STEEM Power, which is analogous to being a shareholder, both in terms of potential payment and potential influence. Blog posting and voting is rewarded here, 50% of it with STEEM Power and the rest may be converted to such a stake if one so chooses. Over time, that power can grow proportionately. Anyone can be a factor here.

With Facebook, Twitter, and Reddit, the only ticket to ownership and control is money. That provides the potential of enormous control. I am not saying such abuse of control is par for the course on a daily basis, but we have seen several prominent examples of that control being used/abused. It is only fair to speculate that the ownership has some influence. After all, the CEO and day-to-day management of each of these social media sites hold their jobs only as long as their efforts reward their real bosses, the shareholders.