>>95832057
It's worth remembering the difference between area effects (and area spells) and explosions (like explosive fireball), but the rules are fairly similar.
An area effect can only target a hit location if the target is large enough that the entire area only covers a single hit location. An area effect can also attack random hit locations by adding the bombardment limitation (presumably spells like rain of stones and rain of ice daggers are similar, but this isn't explicit in their rules).
An explosion, on the other hand, 'affects' all exposed hit locations but doesn't use hit location rules unless only a single location is exposed. This seems unlikely to be the case unless you have a very weird body plan (e.g. an airship dealing with an explosion from above).
However, this seems completely inconsistent with the fact that shaped-charge warheads are generally explosive and obviously should be able to target specific hit locations. Likewise, common sense says that a grenade going off in your hand will cripple it.