Theories on why IMDb message boards were closed (and wiped)

I doubt there was one reason, either. The trolling was a major factor, likely the biggest; however there were larger cultural and political forces out there as well.

It's my sense that the Trump candidacy and election played a part in the boards closure. No, not the political views of the Donald himself but rather the culture that swirled around him, and in addition to that his rather trollish disposition.

It was like a red flag for the board closure partisans, a game changer. Like bartenders in a rowdy British pub in the wee morning hours they cried out: "time, gentlemen! Time!". And so it was.