Blockchains cannot readily read information about the real-world (weather, price, real-world-assets’ existence) and integrate them into their State and domain of authority. For this, they need to trust an external source of truth, often called an Oracle. Existence of these oracles is often a Weakest Link issue.
The oracle problem only focuses on reading information about the real world, but the same can be said about mutating/updating the real world as well.
Argument: For an authority to be Trustless , it needs to be able to readily read the state related to that matter, and readily (enforce or) write mutations to it, regardless of being in the digital or real world.