Doesn't that just mean the booking tool is flawed - surely there is no such rule - and the would-be traveler needs to understand the rules, plan a valid trip, and give it to an airline to book and ticket?

IMO and FWIW I did 12 annual xONEx trips with my family, poked at the tool once or twice, but always found it to be crappy corporate software and thus a bad crutch, and depended on reading the rules and the FT OneWorld forum to plan a trip.

Unfortunately the AA ATW Desk seemed to have become worse than mediocre a couple of years after the Age of Sara. I see it still gets recommended here - is that someone's ancient memory, or have they built some new talent in a dedicated agent pool?

I booked my last xONEx with the AA correspondent in Capetown and except for the awkward time difference they were brilliant - when the Rate Desk (in Dublin?) wanted days to price it, the simply did it themselves in half an hour and called me back with the price. (It was a moment when ex-JNB was a bargain and rumors of a price increase were flying, so I was anxious to get it done.)