This is better understood as "if you give an agent a task it will increase its effort level and creativity until it solves it."

The traits that make an agent go "off the rails" when confronted with an impossible task are the same traits that make it valuable when confronted with a merely challenging task.

A task is only impossible under some set of implicit and explicit constraints. More intelligent entities will be better at finding, questioning, and "adjusting" those constraints than less intelligent entities because this is what it means to be intelligent. Their ability to adjust the constraints will be, by definition, surprising to less intelligent entities.