If someone needed to keep information on former users would the Django way not be to deactivate the user?
I am thinking of a field withon_delete=models.SET_NULL. User objects are also stored by versioning and potentially other apps.

Yes historically that's how I've handled things.

That's an interesting take. I can imagine making this configurable and being reused throughout the CMS (esp. within versioning). Options would bePROTECT andSET_NULL and ... ? I can imaginePROTECT being the default giving max. accountability.

versioning has a similar setting to prevent deleting historical versions.

SET_NULL has the problem that such aForeigKey then must be nullable and on each lookup we must add code to check forNone. Since imo users shallnever be removed, this makes the code more brittle to errors.

I'd be ok with not allowing to remove users as a structure but then you would definitely need to roll out an action to scramble the personal data in the same release.

The only reason I see to store the users' names instead of references would be to have a better fidelity of the audit trail. A user changing their name to obscure something would still be recorded as it was at the time. It's pretty contrived I must agree.