Perhaps it was changed. I remember an old article in our Mage forums on my guild site that had a link to the WoW site and it talked about 8 added resistance. The link was:
WoW Basics: Spells. That link I thought was the one that showed that there was 8 added resistances, but I skimmed and it didn't; it does hold this section though:
WoW Basics: Resistances. The resistances article doesn't have anything stating added resistance either, so it should use some testing.