Mathew Ingram explains that Facebook deletes things, which creates problems for news. This probably could be fixed, esp given that they have now created a new channel for news. They could treat it differently from user-posted items.

There's a deeper problem, however, one that's not easy to address. It's the "access journalism" problem. Today, journalists pay a price if they criticize business or political leaders: they might not be able to schedule an interview when they need one. But with Facebook it's potentially more serious. If they say something Facebook doesn't like, their articles may get less favorable treatment from the algorithm. Facebook may say this can't happen, just as Twitter said the SUL was purely algorithmic (we knew it wasn't), but the doubt in the writer's mind creates a conflict that wouldn't be there if the article was published on an independent site.

Put another way, you can criticize the open web all you want, there's no one who can take offense, and no one that can control access to your writing, and no one who can refuse access to you.