And like I said, you could argue for the implementation of many systems of that account. Again, the question is not whether killable NPCs is virtuous - all player freedom that doesn't break the fiction contract is, more or less - it is whether it is worth the cost to implement.
If there is 0 cost I completely agree that it should always be implemented, because why not.
My entire point since we began this discussion was that given how little you actually use the system and how little value it brings, it is an odd system for so many Codexers to choose as one of the fundamental tenets that must be in all RPGs.
BRO GOODB POINTS
HERE IS THE REAL REASON YOU SHOGK BE ABLE TO KILL EVERYONE
GAMES THAT ALOW THIS USUUULY HAVE A FREEDOM OF CHOICE AND DESIGN THAT ALLOW APPLYING THE MECHANICS CREATIVELY
THISB OFTEN MEANS MULTIPLE SOLUTIONS TO POOBKLRMS AND FREEDOM IN APPLYING GAMGE MECHANICS
INDIRECTLY IT ALSO SUPPORTS DIFFERENT FACTIONS CAUSE NOT ALL TOWNS OR QUEST GIVERS OR MERCHANTS ARE GOOD PEOPLE OR PEOPLE ON YOUR SIDE
TERRAIN DESTRUCTION IF IT WAS ALLOWED SHOUFKD LET YOU DESTROY A TOWN
YOU SHOULD BE ABLE TO STEAL THE MERCHANTS ENTIURE INVENTORY IF YOU CAN STEAL OR KILL MERCHANT
TO PREVENT THIS YOU WOULD HAVE TOWN GUARDS TO KILL OR EVEN BETTER NO ONE WILL HELP YOU IN YOUR QUESTN BECAUSE YOU ARE A HORRIBLE CUNT
WHICH BRINGS US BACK TO CHOICES AND CONSEQOUINCES
PLUS LOLLLOLOLLOL I HAVE FOND MEMORIES OF KILLING EVERY MOTHERFUCKER IN NEW RENO AND LOLLOLOL TRINSIC CAUSE A MOTHERFUCKER WOULDNT GIVE ME A SHRINE MANTRA