[chrisbridgett]

Reddit?

[uchi]

Reddit's userbase grew very quickly after Digg drastically changed, aka 'collapsed', Reddit for a while also engaged in sockpuppeting posts to generate fake traffic to create the illusion of a userbase before it really took off.

4chan, in comparison, has always been organic from day 1.

[ivarious]

But many OPs of 4chan threads sockpuppet their own threads in order to make their thread gain traction.

[simias]

It's not made by the website owner so it still counts as organic

[lmm]

Wasn't founded until 2005?

You could make a case for slashdot or wikipedia or google, but IMO all have changed substantially in the last decade.