This makes sense to me, that since airlines are now accepting each others' e-tickets in the event of flight irregularities that they now have the abilitity to look at each other's passenger records in order to confirm that e-tickets are valid.

This could have dire consequences for booking back-to-back tickets. In the past, you only got caught if you were using the same airline. Then, when alliances and code-sharing came along, you had to make sure that the two bookings were with airlines that had no overlap. Now, it make no longer be possible to do risk free back-to-back bookings.