I would absolutely agree with your thoughts. But tell me this, for the average person coming from Facebook or Twitter or Instagram or Reddit, what is it that will actually make them switch? Rewards.
I don't see any promotional material going out touting privacy, or decentralization or anything else remotely substantial. And for a mainstream audience they won't care to jump ship from their current social media to Steemit for any of those reasons anyways.
So, the main differentiator here is rewards. It's undeniable that rewards are the truly interesting proposition to 95% of the people it will take to get Steem to 10 million users.
How do they earn rewards? Articles and Curation. And right now both favor those with significant Steem Power invested which doesn't favor those switching platforms. If they don't immediately make some sort of noticeable reward, they will bail within a week. When they do, those users will lose/forget their password and keys and this will be a ghost town of account names and a some really passionate crypto enthusiasts who reward each other.