The idea to know that we know nothing is more of an approach than a fact. It’s based on the understanding that when people believe that they know something, then what they see themselves knowing will be true under any circumstance.
Wouldn’t there be change, something known or assessed yesterday might still be true today. But, given the presence of change, knowing nothing will be an approach that eases being in the moment and noticing what is happening or present in it. It requires curiosity. Assuming one knows not only prevents curiosity it also prevents noticing what is present.
Knowing that we know nothing is the frame of mind that leads to mindfulness. It’s a way to be in the moment. And it’s a way to benefit from what one is engaged in doing at that moment.
It’s a different frame of mind than the one people need when they plan something or when they define a project.