Question on Foundation's Triumph by David Brin

SPOILER SPACE, just in case...

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I just finished this book yesterday. Quite a quick read and full of little
Asimov details, e.g. links to Pebble in the Sky and The Stars Like Dust as
well as the robots.

Anyway, one thing that wasn't clear to me was the need to keep humanity
ignorant of its past. They blew up the archives because they thought it
would lead to "chaos outbreaks". Maybe I missed something, but why would
knowing about Earth lead to these chaos outbreaks?

I did like the explanation given as to why there were no aliens in the
Foundation universe!

Jack