Nothing takes the fun out of an online game like cheaters. It's one thing to take on opponents that are simply much better than you at the game. That gives you incentive to work hard, practice, and get better. But if you run into players that don't take damage, seem to headshot from across the map, and can see through walls, you aren't going to have any fun. Blizzard knows this, and that's why they're making sure that cheaters don't ruin Overwatch.