The best reason I can think in recalling my last drunk is in it's usefullness to someone who can relate to it. Maybe someone new, who thinks no one understands the pain they are going through. Perhaps the physical and mental pain, or they were sober for a bit and don't know what happened..the shame etc.
In no way do I think that the memory itself will keep me sober.
Oh yea, there's that "sufficient force" part as well. My history tells me that over and over I haven't been able to keep that pain close enough to avoid going through it again.