It might not be Yahoo alone, but most of us have long been accustomed to organizing information in a hierarchical manner, breaking the whole into pieces or parts by directory, so that we are comfortable calling the starting page “the top page.” 
It is time to think in the opposite. Why not call it “the bottom page,” from which we initiate queries and update our boundaries as we move up along the way.
Update:
reminded me of my favorite quote by Kevin Kelly, which Tom Peters often uses in his presentation slide  (see p19):
“The wealth in not gained by perfecting the known, but rather imperfectly seizing the unknown“