He is trying to advertise himself, and suck up to the other ones that shouldn't be listed.
How is he trying to advertise himself? He's listing clans that have been successful in their existence. He put USSR in the list because it was a highly respected clan that had (some) mature members, and was actually active in its lifetime.
See here in this quote:
a list of clans that have genuinely succeeded, or are in a very upwards direction in terms of popularity or membership.
He's not listing clans that sucked or didn't suck. He's listing the ones that were active and popular. That defines rather a clan is successful or not. If the clan has a few mature members, holds true to its theme, participates in activities, and lives for a good cause is, in my honest opinion, defined as successful.
Mi, for example, lives for an original, and good cause. It helps to promote decent mods. It could be seen as successful, seeing as how it has members who can actually mod, and is active with its activities.
Sirrus is just trying to make a point and state his opinion.
