On an ideal world, there might not be enough incentive for life to develop or get out and colonize. With everything conveniently placed within reach, there is no reason to reach further, no reason to think about passing the next hurdle, because, why would you? It is precisely a lack of resources that causes life to adapt and get in motion.
To develop, life needs challenges, but not such big challenges that they are lethal to the entire species.
so, just maybe, Phoebe is too perfect to develop intelligent life, while Ophion is too lethal to really sustain it.