But if you lurch backwards to avoid the giant sword, and you're calling that HP damage, then how are the characters aware of it? Why would your character think that they need to drink an incredibly expensive magical potion, when they don't even have a scratch on them? Why would a magical healing potion even be valuable at all, if it didn't have any tangible effect? There are too many ways that the world wouldn't make sense, if that was what was actually going on.
Counterpoint 1:
Uh... have you ever had an IV after being horribly dehydrated? I was beat, barely able to walk and 1/2 hour later, I felt fine. If something could do that in ten seconds? Yeah, that'd be expensive.
Counterpoint 2:
You need to go to some better parties, dance your butt off, then *pop* Drink a Red Bull. (It'll give you wings!) If that's not a 'Potion of Cure Fatigue' I don't know what is.
