Why would running scheduled tasks with Celery be preferable over crontab?
Celery is indicated any time you need to coordinate jobs across multiple machines, ensure jobs run even as machines are added or dropped from a workgroup, have the ability to set expiration times for jobs, define multi-step jobs with graph-style rather than linear dependency flow, or have a single repository of scheduling logic that operates the same across multiple operating systems and versions.
Considering Celery is already a part of the stack to run task queues (i.e. it is not being added just for running crons, that seems an overkill IMHO ).
How can its "periodic tasks" feature be beneficial as a replacement for crontab ?
Specifically looking for following points.

Major pros/cons over crontab
Use cases where celery is better choice than crontab
Django specific use case: Celery vs crontab to run django based periodic tasks, when celery has been included in the stack as django-celery for queing django tasks.