think of it like this:
You are the 51st person in line for a theater that holds 250 people.... You wait in line for 2 hours to see a movie... when you get into the theater you look all over for a seat, but the 50 people in front of you are saving seats for their friends, so even though you were there 2 hours early, you can't find a seat. You would be pissed off too, you waited in line, tried to find a good seat, but everyone in front of you is saving seats for people that didn't feel like standing in line and are going to show up later.