Because when they have to line up vs. when they want to line up are so far apart. And sadly in a lot of cases people do lineup behind those chairs.
There's a lot of people I know that will do the same thing. Both times I did it I was just trolling and it was when the whole "ghost chairs" thing started popping up here. It's actually funny because I haven't lined up for a sneaker in 2-3 years? (infrared 6s), but was thinking about doing it for Top 3 1s. Again, was heading home and happened to drive by LS Spadina at like 2am the morning they dropped and saw 2 chairs outside.