We've just had a week of shock and mourning in Ireland because a member of An Garda Síochána - our police force - was murdered when he intervened in a domestic dispute. The person who fired the shots (who also shot his partner and then turned the gun on himself) had the weapon in his possession because of his connection to paramilitaries.
The point being that even though the weapon was not used for its intended purpose, the fact that he had it in his possession gave rise to the possibility of it being used for a different purpose other than that for which it was meant.
Human nature is unpredictable and subject to emotions. And for that reason alone it makes absolutely no sense that anyone should be allowed to legally possess weapons, because they can always be used in an emotive situation where they otherwise wouldn't be if they weren't in the person's possession.
