Active job - in the real world an active job is a job with ongoing work.

Job status is something you can filter on

Closing a job doesn't impact active tickets in the job - you just can't add more tickets to the job.

Changing the job status doesn't change the tickets.

Closing a job just mean that you can't assign any more tickets to that job.

It is completely optional if you want it .

Once a job is closed tickets can't be accidentally assigned to the job.

The status of individual tickets isn't affected by the job status - you just can't assign more tickets to that job.