Because statistically, if I am in a shooting situation, I won't have to hit a gong at 100 yards...instead, I'll have to hit an attacker at under 10 yards.
Statistically the odds I have to hit an attacker at any range is slim. Where as the odds I'm gonna have/want to hit that critter or gong or rabid pop can are at 100%. You may not believe this but most guns are owned for fun not outta fear. Set your drills aside and have some fun for Lord's sake.