Agree, but it can look a little brutal. A couple of weeks back my spouse and I were in 21 E/F and a young lady (under 25) in D. 21 A/B/C were open. I suggested to the young lady she could move to one of those seats for more room, which she did. Then her boyfriend who was in 22 E started to move up to sit next to her. The FA rushed to tell him he couldn't sit there as it was a Premium seat. When he stated they were both on the same reservation and that they had split their seating, he in row 22 and she in 21, the FA replied " Well that's her good luck for getting an exit row seat". Seemed a bit harsh to me, but whatever. The girl did seem to enjoy her flight in the empty row