The choke point
Sooner or later, all big public media companies go in search of a choke point, the place where they can find a leg up in terms of attention and monetization.
FACEBOOK said to you and to everyone else: Build your content here on our site, and we'll make it easy for you to effortlessly share it with your friends and their friends and their friends. Over time, of course, the clutter leads to less sharing, and now you can pay them to promote your work to the very people who used to bump into it for free. They have control of a scarce resource (attention) and they're building a business around it.
LINKEDIN approached many bloggers over the last year and asked them to contribute original posts on their site. In exchange, they'd direct lots of their readers to the content. Of course, it's not hard to see how soon it will become an isolated garden, a platform they own and can charge a toll on. They have control of a scarce resource (attention) and they're building a business around it.
GOOGLE cancelled their RSS reader because RSS is a free, unchokable service, one that's hard to put a toll on. On the other hand, when you build on their platform, you become part of their ecosystem, a click away from all sorts of revenue. They have control of a scarce resource (attention) and they're building a business around it.
Worth noting that GMAIL has figured out (acting, it seems, on behalf of users) how to use tabs to differentiate between "primary" emails and "promotions." If you're used to getting this blog by email, odds are you haven't seen it in awhile, because even though it's not a promotion, even though you signed up for it, by default, it's in your promotions tab (easy to fix, by the way, just drag one of the emails to the primary folder). While this tabbing default probably saves you from emails that are actually promotions, it also provides Gmail with a choke point for the future, because the person who controls which tab an email arrives in is powerful indeed.
I could go on about other companies and other platforms, but you get the idea.
Again and again, we see that if you're not the customer, you're the product. "Free" usually means, "you're not in charge." The race continues to be one for attention.
Tim Wu's book on the history of this process is a must-read for anyone who makes media.