I would be very surprised, to say the least, if anyone got all the way to the banshee - unspoiled - without either knowing about the "more" in the look command and therefore the monster memory or having heard the mad minstrel songs. Before I spoiled myself silly, I'd explored the wilderness and heard the minstrel songs several times over. The 'l'ook command is something players usually learn within the first couple of hours, with no assistance from outside. A player who doesn't look at monster details nor has explored the wilderness enough to find the mad minstrel, but CAN reach the banshee unspoiled, is sort of like a cook who can deliver star-level dishes but doesn't know how to read (including recipes) or use a microwave. Such a person may exist, but it's unlikely to the point that it's silly to make a change in the game just for their benefit, if it diminishes the mystery associated with the banshee so severely.
... I mean, come on. You don't have to be me to know how to use the monster memory. Give ADOM players some credit.