Agents are steamrollers because they have no broader perspective.

They are inside of a box, will know only what you tell them, and when they're done they will cease to exist.

That means that whatever task you give them is the most important in the entire world, ever.

A human is situated; they can see the tradeoffs between different goals, and the long-term downsides of actions.

But the agent lacks all perspective.

The agent will do everything in its power to make the goal happen, come hell or high water.