I read this blogpost titled American Airlines Will Stop Awarding Frequent Flyer Miles and Loyalty Points to Passengers Who Don’t Book Direct. It makes me wonder: why would an airline stop awarding frequent flyer miles and loyalty points to passengers who don’t book tickets directly with them?
I thought that the airlines would be happy to collect their customers' money without caring about through which channel it got the money. The blogpost provides this quoted explanation:
“Not only does booking directly with American provide the best possible experience, it’s also where we offer the best fares and it’s most rewarding for our AAdvantage members.”
But it's rather vague and partly incorrect (e.g., "best possible experience" is quite subjective and nothing prevent a good travel agent from making the experience better, e.g by booking faster for their regular clients). This makes me wonder if there's another explanation that is not in that quote.