Well, that's GW for you. Rules that existed in previous editions get lost in the mists of time. You can see that parallel in their games -- that's how we ended up with a stagnant tech universe in 40k - people keep forgetting things every 10 minutes or so. In FB why do you think the High Elves, who had a gigantic tech head start over mankind, haven't invented crap in thousands of years? I'll tell ya -- shoddy memories and non-archival paper.