Kind off disagree here.

However, the fare class associated with it is L but avaiability is based on B-class fare. That means that if there are B-class seats available you get two of them for an l-class fare.

In my case B-class fares from IAD-ZRH were 514 a pop, making it 1028 USD in total for TWO tickets, where the Mastercard 'Offer' was 1712 USD. Also for two tickets BUT the second persons would not collect miles AND had to fly the same segments at the same time.

So, I think this is really a good marketing plot!