http://www.niemanlab.org/2015/09/what-happened-after-7-news-sites-got-rid-of-reader-comments/
Seems the best of both worlds would be to push the users to social and then embed the social comments into the page. This way you get the publicity and then have that publicity pushed as on-page content which reinforces the articles' reach and encourages further social engagement -- a nice feedback loop.
Yeah, foist the problems and expense of moderating over to FB. It's a good trade-off, allowing a brand to touch base with the followers without really having to deal with them. Other than loss of content, about the only negative I see is you're adding value to someone else's site. You don't own it and that's the point, I guess.