I had played with it a few times, from the 80s through to the late 90s, but had always found the formulation limiting, sort of a finite against the infinite.

And for the search for an "Earthlike" planet, there was always something new to add, such as:

The axis of the Moon's orbit is located within the Earth's mantel, churning it and keeping our magnetosphere charged. A nessessity for the development pf higher lifeforms.

The proximity of our Moon also acts as an impactor shield. Just look at Apollo's map of the lunar farside.

Jupiter acts as an impactor deflector and attractor. Recall Shoemacher's multiple impacts in the Jovian atmosphere, with many splashes larger than the Earth's diameter.

Now, Rob's posted article touting the natural oddity of an oxygen-rich atmosphere seems to be yet another nail in the coffin for the quest for an Earthlike planet.