A lot of that trend (not necessarily in T-Nation's case)was because of internet troll-isms that turn into bad press. They (news outlets) needed a full time monitor to keep thing civil and it just didn't make sense financially. At the same time, they have these other social media channels, Twitter, FB, etc., that always seem under used, so the hope is to drive traffic to them, get "liked," engage the readers and most of those channels have some sort of monitoring, so it becomes a double win. "We're winning social media, and not getting bad press!"
I sat through a few meetings about this in my time, (as a recruiter often as an ancillary to marketing) a bunch of old(er) exec's trying to bottle social media engagement but at the same time never let their branding be victim to some 12 yea old in a bad mood. The punch line is for the most these captains of industry don't understand the basics of social media, they only know it's col, and they should be on it.