The Actions On Objectives Stage is the end of a Cyber Attack. The threat actor has achieved their goals.
In a ransomware attack, this would be the point it has spread as much as it could have until the attack terminated or a total compromise.
The threat actor may still have access to compromised systems on the network. As such, there is still potential damage to inflict.
It would be preferable to catch and terminate a cyber-attack before it reaches this stage.