Instead they let themselves caught up in the 'fake news' fiasco (a factor absent from the article), re-prioritized personal posts, and deprecated their previous actually-kinda-nice attempts to give a proper home to professionally-written journalistic content, such that it's not jarringly intermingled with memes, baby photos, and humblebrags.
Part of their problem, perhaps, is the insistence on using the Facebook brand for their homegrown stuff, which is ironic considering they run parallel services under different names. No doubt a lot of it comes from having to harness the idle time of massive numbers of Facebook users sitting in their flagship website or app, but if they started a news portal with micropayments, cross-pollinated with their network of apps and backed with their identities, they would still do more volume within a month than any of their competitors managed to do so in years.