I think I've come to a conclusion that Nature is a sort of sentient force in this world, a sort of Gaia. Whereas the gods might just (theoretically) strike down a former devotee who "turned" on them, Gaia would wait... who knows, that apple you just ate could have been poisoned.
It isn't? ... did you remember to check the pear?

I'd suppose that a "Fallen" Wanderer would be worse punished than a "Fallen" Ranger or Druid, as they're less permanently "bound".