<Snipped quote by Willy Vereb>You talk about two different things.
In theory, they can - and in some ways, that's the point. Otherwise, nothing really stops people from making it, effectively a one on -insert number of NPCs/minions.- SKallagrim vs DJAtomika played this out well, but then again, Skallagrim isn't the type to nuke all the NPCs at one time without sustaining some type of damage in the process.
In general, or at least to me, the NPCs/Minions are really different words for the same thing. Random mooks designed to be destroyed. Nothing, however, stops you from controlling the ones you have left to make some type of attack against them - and hope to the high heavens you aren't going up against someone who'll stand toe to toe with 100 minions and defeat them all in a blur that rivals that of the blur in Smallville.
If somebody does a "lazily insert random number of enemies to beat X" then it's either a clear abuse or the character explicitly has such power and then he's probably up against people who are on similar level.
What you describe is very much the same as somebody instantly destroy your swords, disarms you and then render all your powers useless. These are done in a plain unavoidable autohit abuse.
Would you recognize this as being fair?
Autokilling minions is the same.