Originally posted by DarthAnt66
To clarify and summarize the preexisting material. Some sourcebooks even create new content, in which those claims would be primary.
Clarify material with a lifespan of however long it takes for material on the same subject to come out? That's ridiculously short - you're proposing a method of continuity so fluid that we can never have an established universe that doesn't get reorganized every week.
And your distinction between primary and secondary would serve our point - if the purpose of the latter is to clarify the former, then the blurb clarifies that Plagueis's claim to being the most powerful ever was accurate. Done.