Currently, teachers can edit activity completion in bulk at course level.

It would be useful to have that setting at site level as well, so site admins can choose what the default tracking setting is for each activity.

Better UX: teachers will have one less thing to think about when they are preparing their content and admins can make sure that courses are not cluttered with checkboxes for activities that don't always need to be tracked, such as labels.

Better consistency: this will also make the experience more consistent with other settings, such as notifications, which can be turned on/off by admins but also turned off by each user for their individual accounts.