Rain World "world" shoudn't have a crazy climate?

A simple question, if the natural ecosystems and the destruction of the natural planet, that the Ancients did before disappearing, even with probably millions of years, shouldn't the climate be crazy? I know Iterators heat up the atmosfera, but this wouldn't help even more with climate collapse? Would be expected to the planet having extremely high temperatures, unfunctional temperature variation, water intoxication (Not exactly about the climate, but about damages in the ecosystem caused by the Ancients), more natural disasters, and we don't see anything like that.