Why does everyone assume the churners are getting away with something or duping Mileage Plan? I'm pretty sure there's been plenty of cost/benefit analysis done by AAG/MP, and that it's a net positive. My guess is that Bank of America pays more per mile awarded in credit card signups than Alaska pays their partners for redemption purposes. Perhaps that's why it continues - much to the chagrin of those of us who earn a good part of our rdms by flying?