In Scrum, self-organization and empowerment are fundamental principles. Allowing existing teams to propose how they would like to organize into new structures respects their autonomy and encourages ownership of the process. Bringing all developers together to let them self-organize into Development Teams aligns with the value of self-management, enabling teams to form based on mutual agreement and collaboration. Assigning individuals to teams by managers or a Chief Product Owner contradicts the principle of self-organization.