Could be, but I now think it was more a case of not asking for the correct document when in DFW. I just got back from AA's SCL office and I think I now have the complete picture:

When asking for a copy of your e-ticket if you don't ask for a -receipt- you get an -itinerary-. AA's SCL ticket office just printed BOTH for me and the receipt is what you'd expect: a duplicate of the actual ticket, number included.

Feel 'safer' now. :)

Further to the discussion regarding HEL/AY and e-ticketing, from finnair.com:


FINNAIR E-TICKET HAS ONEWORLD COVERED

Finnair’s e-ticket interlining now covers all eight oneworld airlines, namely Finnair, Aer Lingus, American Airlines, British Airways, Cathay Pacific, Iberia, LAN and Qantas.

This means Finnair customers can travel with just one electronic ticket and a single check-in procedure to any of the oneworld alliance’s 602 destinations in 136 countries.

oneworld airlines focus on service. The e-ticket offers passengers considerable advantages. It makes connections between flights by different airlines smoother, easier and more reliable, and reduces time and hassle at airports. The e-ticket is also safer than a traditional paper ticket as it cannot be lost or stolen.