Shipments with a digital delivery method can be useful for items that are digitally delivered to the customer (via email, third party system, or otherwise). In these cases you don’t usually track inventory, but you do rely on the deliver state of the shipment to determine if you’ve emailed the customer.
In this case I think we’re talking more about things that have no delivery mechanism. You’ve got more options with those. Definitely done track inventory on them, but it’s really up to you and your downstream fulfillment tools what makes the most sense.