Airlines are looking for new frequent flyer members and are willing to front bonus miles to get them. Traditional frequent flyers aren’t traveling so much now, and flights have a lower proportion of members than airlines are used to. They need a marketing relationship with the people who are flying, in order to encourage them to fly more and take their credit cards.
With Alaska’s renewed partnership with American Airlines, oneworld membership starting March 31, distance-based earning (not revenue-based!) and pledge not to devalue their award chart without notice they’re likely a strong option for many.