Let's take an existing article, which already has some categories: http://en.wikipedia.org/wiki/Anne_Frank
It has a fairly small set of current indexed categories: Categories: 1929 births | 1945 deaths | Diarists | Dutch writers | Murdered writers | Holocaust | Dutch World War II people | People with asteroids named after them
The Anne Frank article also shows the limitations of the Category feature. Do we need 200 categories just for born in, died in XXXX? Instead the "people" index would contain name:Anne Frank, born:1929/06/12, died:1945, nationality:german... And the "events" index would contain memorable moments of her life. With a more database like aproach - a table with fields. Searchable. And then you could also open the original pages you found, if you want to know more.