The history behind it is that when QF first built qantas.com it allowed web site users to request cities to add to the drop-down list. Which led to hot destinations like Papa Westray to be added to the QF drop-down list -- until QF realized there were thousands of such airports and it was running out of real estate. List was frozen and then trimmed down, ending up with a somewhat irrational pull-down that we have today (and forever more). Listening to customers leads to fine solutions (or not), esp. on the web. You would think there would be a Oneworld key city list that all the Oneworld airlines use, but that's not the Oneworld way.