wow that's interesting! I haven't used the FB api in a few years now (using it was how I bought my house). That totally sucks.
Facebook is doing it right now with messenger chatbots and Amazon is doing it with Alexa.
News feed spam that makes Facebook money is allowed. Spam that doesn't is not.
[1] http://www.bloomberg.com/news/articles/2016-07-30/shanghai-g...
There were tons of people selling sheep-throwing apps and whatnot back then, and it wasn't uncommon to hear of deals in the hundred-thousand dollar range. Then FB killed the virality.
Pretty much every time Facebook releases a new feature, some lucky sod gets rich. See also: Socialcam, which failed to gain any real traction, but got early access to the feed API, and leveraged that into a pump-and-dump.