Trolling is the inevitable reaction to groupthink. Predictably, groupthink is interested in ways of insulating itself from trolls.
The word 'trolling' seems to have taken on many definitions of late, you are probably using a different one than the article.
I understood the article to mean troll in the sense of a person purposefully misdirecting discussion to make people angry (note that the troll in this sense usually does not believe what they are saying, they're "trolling" for reactions).
It sounds like you are using the more recent use of "trolling" to mean "to disagree with someone".
That's not a definition of trolling. That's people in arguments mistakenly calling their opponents trolls.
I don't think parent is saying "people who disagree are trolls" but is saying that some forms of groupthink encourage trolling behaviours. When your wikipedia edits get stomped on by Twinkle-using 13 year olds on Vandal Patrol who are gathering reverts to apply for admin some people react by leaving; others react by trolling.
(As I understand it WP has tried to address Vandal Patrolling; Twinkle misuse; reverts for adminship; etc).
It sounds like you are using the more recent use of "trolling" to mean "to disagree with someone".
The study authors do report that there's a propensity for polarization, i.e., that "we find a community bias against FBUs: posts written later in an FBU’s life are more likely to be deleted, regardless of whether they are actually worse".