On that note, is it necessary to restrict (player_faction) to official factions? I mean really? Because that means that every time a faction goes official, unofficial, dies off, is sanctioned, etc. etc. - that a bazillion links in their posts will be invalidated (barring redirect logic use).
A faction is a faction - faction does not imply 'official', it implies organised. And if they're organised enough to have a Wiki page, chances are they're official or soon to be anyway. [/opinion]
Edit: It also occurs to me that unofficial factions (at least GRP, I'm using them as my example) aren't actually listed on the player factions page. To make a contribution, I humbly suggest that we keep all player factions, dead or alive, official or otherwise with the (player_faction) tag, but either:
a. Create a reference / links page for official factions, and a separate one for dead, unofficial or otherwise (they create and manage their page at their leisure)
b. Add a column to the Player Factions page named 'Official' with ticks next to the appropriate factions.
This ensures that links aren't broken, but officiality or status is documented where the faction is. In the event an unofficial faction dies off and a wholly new faction wishes to use the same name, they could use, replace or modify the former faction's page.
Edit: Obvious mistake noticed in the fact that the afore-suggested separate page exists. However, my point about keeping them all (player_faction) to preserve links remains valid. Which is fixed by using redirects. :$