100% - the Project Owner is the 'Champion', the person pushing both 'downwards' and 'upwards' to ensure that the project is successfully implemented. The Project Manager is the person on the hook to meet all deliverables as per the project timelines and to escalate when necessary up the Project Owner of any roadblocks that they themselves can't unblock.
The more invested the Project Owner is, the greater chance of success the project will have.