Don't even get me started on codeshares.

What's the point of a global alliance if benefits don't extend to travel on the alliance partners?

My examples in the OP were based out of MIA, but I've spent hours the past few months checking prices out of RDU and STL for the double elite qualification miles promotions. It's much harder to fly AA metal and qualify for the promotions to Eur or the Pacific out of those cities than to fly DL. (DL metal does fly to SYD!).