Exhaustion perks give a survivor a sudden movement advantage - a sprint, a dash, a long vault - and then apply the Exhausted status, which prevents any other exhaustion perk from firing until it wears off. That shared cooldown is what stops them being stacked.
They are the strongest category of chase perk in the game, because a single well-timed activation can reset a chase that was about to end.
Competitive rulesets restrict them heavily for exactly that reason. DBD Arena allows a survivor at most one exhaustion perk in a duel, and bans several outright, so a round is decided by how the tile was played rather than by which button was pressed.