A few years ago someone in oneworld told me it was at QF's insistence.
At the time I was querying why the on-line tool was charging for Asia even when I was trying to have a surface segment from SWP to Europe/Middle East. This was a few years before QF changed its flights to Europe to be via DXB. (the end result of my query was that the words "or by surface" got added to the rule)

To address your point - my understanding is that the rule has been "if you touch it you pay for it". So BA's Europe-SWP (i.e LHR-SYD) flights do touch Asia and so you pay for Asia. But QR's DOH-PER is non-stop (as are its DOH-MEL flight and QF's DXB-SYD/MEL flights). IMHO, there is no justification for being charged for Asia on those flights.