I personally disagree with the parent but you are misrepresenting their argument. The person you are responding to is referring to the thesis of the article which is 'as a community grows and strangers saturate the regular encounters, so declines the ability of that community to exist in a meaningful way'. They are using 4chan as an example of this thesis in action since the community of 4chan has a self-imposed growth limit due to the nature of its culture (most people couldn't handle it).