The problem with nerfing demo is that it's like a rusty nail holding TF2 together. Sure, if you look at it itself, demo is really overpowered, but the fact of the matter is that stickies are kind of a double edged sword as far as game speed goes.
Without traps small teams wouldn't need much cohesion, without stickyspam large teams' passive play would be incredibly overpowered, and if either of them were weakened enough to stop being "annoying" then all of the game's other problems would come to the forefront in massive blatancy.
Stickies are like the medigun. They're one of the handful of things that make the entire rest of the game tick. This game could definitely use a lot lot of balance changes but picking out one thing at this particular stage doesn't make any sense.