This is what you guys get for requiring abstracts rather than full papers.
True that. On the other had I would probably never present if I had to submit a full paper. Nearly every conference proposal I have ever submitted was an abstract of something I wanted to write, and proposed as a way of lighting a fire under my own butt to get me writing. Anyone else do this?
Absolutely, I do this. I used to vow that I wouldn't keep doing it, and then I hit the tenure track and smartened up to the ways of the heavy teaching load research stream.
And even full papers doesn't prevent people from switching their paper around. I'm happy if my co-panelists actually have papers written, keep to their time limit, and are at least close to the initial panel call.