Another problem against this method is, the tube is round and small in diameter at that, making it structurally much stronger than a large, flat surface, so it would be more resistant to any forces trying to pull the dent back into a proper cylinder.
I was broadsided by a car while commuting home from work a bunch of years ago. The seat tube had a "pucker" down near the bottom bracket end. Peter Weigle was able to work out the pucker so that it is invisible, rather than replace the tube. I'm guessing rolling out the dent or filling it in are better options. Stickers to cover the dent work, too.
