I doubt that oneworld partner Iberia knows and can/will do, what is asked here from Singapore Airline.

But anyway - those Alliances (for me StarAlliance) improve my (status holding) travel- (example rtw-tickets), comfort- (examples: most lounges, check-in-privileges: special desks, more luggage allowance), mileage-earnings- (status miles with each carrier), mileage-spending- (free tickets on each carrier, upgrades on UA and LH) expierence and - possibilities and - options a lot. I wouldn't want to be without anymore.