Because it's shitmons for shitmons. When I surprise trade in game, at least I usually get breedjects in cool balls or can feel good I gave some kid a rare Mon for his route 1 shitmon. Usually I surprise trade shinies I find that I already have.
At the home level, it's just people recycling the same pool of like 500 mons. If you ever get anything good, someone pulls it, and puts a shitmon into the cycle again. Secondly it's removed from the games, so I'm not even going to bother moving it to a game.
