As a manager, you need to have the big picture of everything going on. However, your team members might know important details that you are not aware of as it is specific to their work or expertise. OKRs are all about little details that impact what works and what doesn’t. You need to hear different points of view and different experiences to make the system work and increase engagement and flow. Also, just cascading plans without any discussion can demotivate the team and that is definitely not what you would want.