Indeed, I think the real thing to look at is all the selling of miles and promotional tie-ins as a profit center. Maybe that wasn't the original intent - and there are real concerns about the widening imbalance between unredeemed miles and available seats - but that's the kind of thing we have today, at least in the U.S.

For a good argument on how powerful the idea is/was, look at the Asian and some European carriers that don't do FF programs particularly well, but find they still have to offer something. Korean, Japan Airlines and Malaysia Airlines have always seemed like laggards there to me, especially loath to award miles across alliances on their domestic routes. You also don't often get double miles for elites except in the U.S. All the promotional tie-ins, non-flight miles and elite perks are definitely cases where America has led the world and is still far in front.