Originally Posted by moondog

Sure, during IRROPS situations, alliance partners are often prioritized for reroutes, but there honestly isn't much of a difference between AA, UA, BR, CI, CX, SQ, JL, NH, PR, et al from Delta's point of view (i.e. just ask for whichever routing/carrier suits you best, and they'll usually oblige, as long as there is space available). Things were a little different before the JVs took root; back then, the alliances functioned more in the manner that you seem to envision (but, customer preferences still mattered).