Because of its newsfeed algorithm, Facebook is way more successful than other social networks. But the advantage to show users relevant posts that occured when they were away turns into a disadvantage when it comes to live coverage - some posts are only relevant in a very small, near realtime window. And since FB is chasing TV advertising budgets like crazy, becoming the preferred second screen (also in visibility, because in volume they probably are already) may also be a priority A objective.
To achieve that, Facebook just announced a new arsenal of second screen tools, like app voting and polling, a photo and video submission app and more. Event-, show- and sports-TV will love this.