I am looking for responses to this question and I'll post a bit of my thinking here as well.

There is definitely value in our interactions online. Companies like Google and Facebook have found a way of capturing some of this value which is reflected in their market caps. The main way these two companies make money is by selling advertising (correct me if I'm wrong, this whole post is off the top of my head and I don't know everything).  

People who want to advertise get to feature more prominently to users than they would "organically" through Google or FB's algorithms. In some ways this could make the user experience worse since it perverts what is theoretically a good algorithm for predicting what users want to see. On the other hand since advertisers want to be profitable they have to be advertising something that will earn money (i.e. people deem it valuable and worth paying for). An advertiser that makes less money from people coming to their site than it costs them to place the ads will eventually go out of business and stop advertising, thus ensuring that user experience is not degraded with links that are not useful for users.

In some ways advertising is like an extra filter  for content. Starting from a solid base of advanced algorithms that predict what we want to see, an extra layer of results come from the Darwinian free-market approach where money is the resource that keeps you alive and only the best survive. So while advertising can be a positive thing for users, it is the Googles and FBs that reap the financial rewards. And why shouldn't they, they've built a useful system.

Perhaps this is the type of system Steem will become. Paying to make your post more visible, taking a risk that people will enjoy it and you will make your money back. Or perhaps there will be professional curators that will stake their money on promoting posts in hopes of a payoff.

I still need to look into how the mining and hosting and all the other specifics work here to get a better idea of how and if Steem will work (I've noticed it relies on the centralized Reddit and FB to prevent sybil attacks) but for now it's definitely interesting.  

I haven't even got into all the other sources of value that can be tapped from social networks such as training artificial intelligence so lots to think about.

All responses welcome. 
Cheers