> Water which is evaporated is also returned to the ecosystem. It falls back out as rain.

This is about as useful as saying "the water stays on Earth". The ecological damage entirely depends on the nature of the water source.

The most poignant situation is non-rechargeable aquifers. When water is extracted, the mineral structures collapse and the storage capacity is forever destroyed.

And as the other reply stated, evaporation (as from evaporative cooling) exports water out of a catchment basin so that it can't be used downstream, just as if you pumped it away.