My advice would be to respond along these lines:
"I can understand your concern that throwing a rock at an enemy might seem 'silly' compared to throwing weapons designed for that purpose at them. But keep in mind that Improvised Weapons are supported by the game as an option. Note that while it does do as much damage as a dagger, there is a downside - they lack a proficiency bonus, so it is much harder to hit the enemy in the head. You can chuck a rock at someone, but you are likely to miss - but if you hit them, it will definitely leave a mark! (No pun intended.)
I can understand your concerns, but both the rules and the DM find my actions acceptable and reasonable. Not because I found some loophole to be 'cheesy', either - this is using the rules for improvised weapons precisely as intended. If you feel they break your immersion in the game, I would recommend talking about it with the DM, or sending customer feedback to WotC."
"I can understand your concern that throwing a rock at an enemy might seem 'silly' compared to throwing weapons designed for that purpose at them. But keep in mind that Improvised Weapons are supported by the game as an option. Note that while it does do as much damage as a dagger, there is a downside - they lack a proficiency bonus, so it is much harder to hit the enemy in the head. You can chuck a rock at someone, but you are likely to miss - but if you hit them, it will definitely leave a mark! (No pun intended.)
I can understand your concerns, but both the rules and the DM find my actions acceptable and reasonable. Not because I found some loophole to be 'cheesy', either - this is using the rules for improvised weapons precisely as intended. If you feel they break your immersion in the game, I would recommend talking about it with the DM, or sending customer feedback to WotC."