Maybe I am dense, but I don’t understand why an airline would favor this. Lets look at two frequent flyers:

Frequent Flyer 001 – has 200,000 miles in his account, all from flights and flight bonuses

Frequent Flyer 002 – has 250,000 miles in his account, 200,000 from flights and flight bonuses, and 50,000 from partner/affinity miles.

Why would an airline favor 001 over 002? Don’t the airlines sell the partner/affinity miles to hotels, phone companies, credit card companies, etc? If so, it should be a profit source for the airline, not a reason to downgrade that frequent flyer.

As Denzel Washington said in the movie Philadelphia, would someone please explain this to me like I am a four year old.