Summary

Game players have tendencies and patterns of use that can be incorporated into game tests for the purpose of testing the game the way players play the game. The point of doing that is to find and remove the bugs that would show up when the game is played in those ways. If you are successful, those players will not find any bugs in your game. That's good for them and good for you.

When you sell millions of copies of your game, "rare" situations can happen a number of times over the life of a title. Tests based on inverted usage profiles can emphasize and expose those rare defects in your game.