You have one system that "wants" you to rest so you advance story line. This typically happens after a plot point, such as discovering or ending a quest, or updating a dialog option for that character. This also happens after pushing the tadpole and "leveling" it up due to use.
On the other hand you have a system that typically limits how often you can rest, and was used to replenish resources after difficult or long encounters. Handing out too many rests, lessens the difficulty of resource management and reduces the reason to have short rest and other resource replenishments based on short resting.
So if limited long rests were required, it would make resources more important (supply and demand, less "supply" of long rests, more value/demand of it)....but it would hinder story development....unless long rests are only provided "upon" triggering a plot point in the game. So only after you use the tadpole in a conversation and advanced the story past the goblins or found a new ally, or completed a quest. That way story development can still happen as required and resting is reliant on advancing the story.
Otherwise, arbitrary limits would have a domino effect/tug of war on the two mechanics.
Come back to the exhausted mechanic....if you advance too many stories you become fatigued and it becomes harder to keep going. Should there be a reward for pushing through the story though for players who better micro manage resources? Or should efficiency be punished?
