When Bob sends a task to the assignee, this task might include details with employee information.
For example: start date/end date to IT team or salary after promotion to employee.
Assignees (IT; employee; etc) are not always exposed to that data in Bob (IT can be restricted from Lifecycle, employees can be restricted from Salary if it's their own).
Therefore, we need a task list owner, as the whole task list is based on the owner’s permissions.