User blog comment:Dopp/Technical Update: June 28, 2011/@comment-3416406-20110628195207/@comment-1066636-20110628233432

The category page may have content, but the category itself has not been added to the category tree - which is a significant part of the purpose of categories. Ultimately, categories are there to help people find articles, and if they are not added to the category tree they are a lot less good at that.

To be honest, I don't quite see what you're hoping to accomplish with this change. Please at least include a preference option if you change basic functionality like this; I'd very much prefer to have non-existent categories to be red-linked.