In the local context, it’s switching characters in the forums to post in support of another character’s posting. Imagine a puppeteer with a sock puppet on their hand. The puppeteer says something and then the puppet “speaks” in support.
The WoW forums are unique among the Blizzard forums in that one account can have up to 50 faces – individual WoW characters – whereas in most Blizzard game forums, a player’s only identity is their single battletag.
It’s a general online phenomenon, present all over.
https://en.wikipedia.org/wiki/Sock_puppet_account
(Sorry for the non-live link.)
So sockpuppeting can be a problem here sometimes. OTOH, it can be detected with a little research in the Armory. So it’s not a technique a skilled miscreant would use here.