Two jobs ago, my employer forced me to fly Delta and forced me to fly out of Birmingham despite the difference in distance from my house to BHM compared to ATL being less than 15 miles. I can confirm this happens all the time. You've not lived until you were supposed to be on the first of three flights they were "forced" to stack into one and you know you could have driven to your destination airport and back by the time your plane takes off.
Hell, Universities oversign all the time ... why not the players. http://www.cbssports.com/collegefoo...2228/recruit-dj-law-signed-with-three-schools
I fly Delta a lot, as well as United. I have way more problems with United at O'Hare than I ever do with Delta. Overall, though, I still fly United more because a FF ticket requires less miles than Delta.