After various experiments, I think people have figured out that the #1 way to make money on mobile is to have a stream of information that people willingly spend lots of time in. You just inject ads into that stream and bingo: profit. It's much harder for Google to win big here because while they have a very useful tool, people don't linger in it. They usually use it to get in, get what they need, and get out.
Twitter says hi
They now run Moat tags on the site and just added new targeting options based on interests.
The feed frequency has also increased.
The only reason they aren't doing it faster because the frogs are getting frisky.
*"Reddit is a pot of frogs slowly being boiled"
I think you also need to close your API if you want to fully milk your streams.
Take a look at the Oracle case - Google pays billions of dollars a year to Apple to have their search on iPhones. And it's not a flat fee, it's a percentage of revenue.
Facebook doesn't have this problem because there is no other social network. Search engines don't really have network effects, facebook does.