[Attrecomet]

ASOIAF however portrays a very clearly medieval society -- vassalage (badly used in the story, but obviously meant to be quite feudal), the general tech level with castles (not palaces!) and the language used are all meant to evoke a late medieval feeling. What Rome did with Carthage is pretty immaterial in this context, because no medieval European ruler would have either the inclination or the ability to enact such destruction.

I'd also point out that destroying an entire city is not total war. Brutality in war and targeting civilians isn't enough to be total war in itself, especially if it's limited to exceptional circumstances -- in general, Rome was extremely happy to conquer new populations to increase their ability to extract wealth.