Ever need to build a content model with related child records? Want to build a Drupal based billing application? Need to model an educational site with master course records and child schedule records all in the same displays? Want to have lightning fast related content displays across 3 or 4 content types on the same page? Need to have your content entry UI's be intuitive and slick?
With a small IA footprint, entities, simple views and a little thinking "out of the Drupal box", this concept becomes a breeze.
p.s. not a single taxonomy vocabulary or term in sight with this approach :)