[andreyv]

First person shooters. Vertical synchronization causes a noticeable output delay.

For example, with a 60 Hz display and vsync, game actions might be shown up to 16 ms later than without vsync, which is ages in FPS.

[play_ac]

Key word here being "might". What actually gets displayed is highly dependent on the performance of the program itself and will manifest as wild stuttering depending on small variations in the scene.

I've seen no game consoles that allow you to turn vsync off, because it would be awful. No idea why this placebo persists in PC gaming.