http://bits.blogs.nytimes.com/2013/03/03/disruptions-when-sh...
-- implies that Twitter has a better model because you still see the same tweets in the same order even with a sponsored tweet up top, because tweets always come in a chronological order.
Maybe that works for Twitter, but I know I don't check my own tweetstream as often as I do my Facebook newsfeed. If FB showed me everything my friends and acquaintances did by default, including everytime they did something in Farmville2, I'd be less inclined to check FB.
And it's not a fair comparison because the FB newsfeed shows a variety of actions, from wall posts, to a posted picture, to entirely new photo albums...Twitter shows, for the most part, one kind of content: tweets.
I'm not saying that the OP isn't right here, that FB's model at its core could be problematic. I'm just pointing out that it's an advertising system that is a consequence of "weighting" the importance of each feed item.