The motivation for this trend is to hide the comments, as blog comment sections tend to be of low value for controversial stories, despite algorithms that can correct for low value comments (e.g. upvoting/downvoting). The fact that Reuters is removing comments from news stories completely indicates that Reuters is lazy and doesn't want to deal with negative comments at all or find a more practical solution for user interaction. Note that the Reuters Facebook page has just as many if not more low-quality comments. (example: https://www.facebook.com/Reuters/posts/837804776239880)
The "everyone is talking about it on social media anyways" rationale is a terrible excuse.
NB/Disclosure: I received most of my internet fame/infamy through my comments in the comments section on TechCrunch articles.