That's another misconception thrown around a lot that has no base on reality. Online posters don't actually represent a large part's of a game community.
A game community is everyone who own's/play's a game not just the ones that interact in social media.
What that means is that posters are usually a very small minority of a game's player base.
5% to be more exact, according to data provided by an industry dev.
Source checks out:
http://askagamedev.tumblr.com/tagged/Star-Citizen