... just ruins the progression in the game.
It depends on how you conceive of "progression," really -- linear versus not-quite-as-linear.
But you can not really make a game like this in a non-linear fashion, unless it is by DESIGN that the player must be slaughtered and reload the game, which wouldn't make any sense at all. Just randomly throwing in mobs that are 5 or 10 levels higher than the player would just be there to auto-kill the PC (you know, kind of like that grave near the docs house). It's just pointless.
