The issue comes down to where the line is for separate options. You're not exactly playing "Core Rules" without the exhaustion mechanic in place. You are tipping the balance of difficulty because you can perform any actions you want for as long as you want without the threat of exhaustion.
If exhaustion is toggleable in any difficulty, what other mechanics would be able to be switched on and off? Idk, but in BG2, if I used the haste spell twice before resting I became exhausted. That's just the way D&D rules work.
It is a fact that the one that set up the choice to begin with is the GM. It doesn't just spring up out of nowhere.
Who else would have set up the choice? (Have you ever been a GM btw?)
I have been a GM for 3+ years, so yes. As a GM I decide what the villain's goals are, but I have no bearing on what the players decide to do. I have to adapt my villain's actions to respond to what the players are doing. The world has to feel like it lives and breathes. I present challenges, but I don't offer solutions. The players must come up with the solutions.
A great quote from Matt Collvile:
"A GM doesn't solve the player's problems, they solve their solutions." A GM presents the problem at hand, but the players decide how they want to solve it. The GM then figures out how to make the player's choice a reality.
1. They decided to rest instead of pursue the horde. Well, the horde ran through a farmstead and burned it to the ground.
2. They decided to pursue and risk exhaustion? They are able to save the farmstead but the fight is that much harder because of exhaustion.
3. They decide the reward for defeating the horde is not worth it so they abandon the quest entirely.
The GM sets up the scenario, but the story doesn't end one way or another. The PLAYERS must decide which route to take.
