Die englischen Regeln sagen ja:
"You can play Resource Cards that don't match the symbols on a Dungeon Card. If you're facing a Dungeon Card and don't have anything useful in your hand, you can play non-matching cards just to get rid of them and draw new cards.
But use this strategy sparingly! Unlike discarded cards, cards played to the middle of the table cannot be recovered by healing cards or abilities."
Was ja sogar selektives Abwerfen möglich macht. Du kannst das gerne als Hausregel sehen, aber die englische Variante beschreibt zumindest das unpassende Abwerfen in der Mitte explizit.