I worked with the Wikipedia category system a few years ago, and you could see the problems with hierarchical tagging systems right in action back then. (Though it may have gotten better in the meantime) The system appeared simple: There were just two relations, "Article A is a member of category B" and "Category X is a subcategory of category Y". However, in practice, the community was using this system to represent…
Ontologies are like languages. There is no correct one. What matters is how good a fit it is for the problem at hand and that you’re all using the same one! If half the people are using Italian and half Spanish, it’s going to be a disaster. I wouldn’t use APL to write a UI and I wouldn’t architect a computer system in Shipibo.
Similarly, if I’m bird watching, “Birds of Northern California” is very useful. Organizing them by genus is less useful to me in that moment, but it’s not wrong.