Originally Posted by
Rivarix
And why would the first airline care whether the second airline save significant money?

It cares when both are under common ownership (hence why CX still provides the service on separate PNR as long as the second flight is on CX/KA) but in the example above, why should CX care that interlining saves AA significant money?
Because cooperation has a better net outcome. Because these individual transactions go both ways. If you buy a ticket interlining to AA, there's a good chance that you are interlining back to CX on the return journey. If not, plenty of other people are.
In the case of airports, the airports charge the airlines for their services. Causing those services to be used more will simply encourage airports to raise their fees. Long-term, either the airline or the passengers will likely pay more.
Plus, the fact that this is a service industry and providing users with crappy service is bad for business. Added to that, there's the issue that travel agents can book multiple tickets together in one PNR to circumvent the new rules, which means that the only winners are travel agents.
It's a win for everyone but the airlines hence why they stop it. Otherwise, don't you think airlines would've continued to offer it?
I would, yes.