Use Case 1: External forms that are only available to complete during a specific date window.  To make these forms more seamless, we use date fields to control access to the fields with Show/Hide rules.  If the form is accessed outside of the window dates, only a Custom HTML message is viewable with instruction on when the form can be completed.  This allows for the form to stay live and public until the next date window opens for submission.

Use Case 2: Control the ability to complete an external form only once.  When an external form is completed, we save data to a DB.  If the form is accessed again, we use lookup rules to verify if a submission was already completed.  If a previous submission is found, the submission fields are hidden so that it cannot be completed again.  (Often used against an ID and a school year)

The Save as Draft button cannot be hidden to accommodate a clean form for either of these scenarios.  Not only is this not aesthetically ideal, but often external users will click the button anyway and the drafts have to be removed before the next window opens or the next batch is available.