Whilst the requirement for only two people in a certain guild to have an achievement for a boss kill speeds up WoWprogress' identifying of kills, it also has a rather annoying side effect. Should any 2 players from the same guild purchase a ToT hc boost, their guild will be flagged as having completed ToT HC on that day, and a ranking will be attributed.
Taking my own server, Kazzak-EU for example, a guild which has been on the server since 2012 (ruling out the possibility of a transfer) and completed their first ToT normal mode run last week, is now ranked as the world 81 10 man guild, courtesy of 2 players killing Ra-den 25 man (and the other bosses from Durumu onwards) on the same day.
Whilst I am in no way criticising boosting or the purchasing of boosts (people can do whatever they want with their gold), the consequence of inflated rankings is both annoying in terms of a yard-stick of where one's guild actually are in the greater scheme of things, but also in terms of recruitment, as rankings are a way by which many players choose which guilds to apply to, and should they be unaware of this inflation, one's own guild can seem outside the boundaries of where these players hope to be, even though they actually are.
Perhaps I am being a bit pathetic here, but I feel that it would benefit others that they might be made aware of this phenomenon.