[derefr]

I don't understand what you're saying. The reason it is useful to make this distinction, is to explain to people that don't see the distinction (and thus assume that, for example, someone who likes math watches Firefly; or that someone who collects MTG cards will be able to fix their computer), that in fact there is a practical difference between the two categories, and that they should keep them in mind so as to not offend people that aren't both by assuming they have traits of a group they don't.