The information was in an inconvenient location. No one assumed that it would be helpful. People were pressed for time (at least they thought they were) and the tendency was to focus on what everyone else was studying. Precedent had set some informal boundaries. You would have looked strange if you'd looked elsewhere.
No one wanted to look foolish and no one wanted to raise questions. As a result, the information was not reviewed.
And that neglect helped to produce a disaster.
The disasters can be so much more informative than the victories.