When a founder is working alone to get traction for the initial idea, she is doing it because of her motivation, which for the sake of argument, let's assume is to have a positive impact towards the problem she is looking to address.

At this point, her actions are solely aligned with her own motivation.

At some point, she brings on more people onto the team. Now, some of them might share with her on what motivates them. But others might be motivated by getting rich, learning new skills, treating this as a stepping stone for other things in their lives, etc.

The higher the variation in the sources of motivation among the people working together, the harder it gets to rely on each other to make the right decisions for the company or project as a whole.

This is where a structure comes into play.

It helps put in words explicitly how to handle situations that arise due to a conflict in the sources of motivation among the people working together.

Structure, at the core of it, helps in aligning motivation.

Though we'd like to think we are the same person all the time, we are quite different people at different times. Who we are on Monday morning is not the same as who we are Friday evening or Sunday morning. Our motivations differ depending on the time and the environment, in however small ways.

The structure that helps align these different people and their motivations in us is our value and principles.