ProjectLink routing - Include document as an attachment

I had a question from a user today: When routing a document in ProjectLink on Step 3. Specify Instructions there is a checkbox to "Include document being routed as an attachment in email assignment notification"

When the email gets delivered there is no attachment. Is there a property / prefence that needs to be set to allow the attachments in the email, or am I missing the point of the checkbox?

I did find SPR 1873048 that stated

On the Routing Process definition wizard, the wording/­description for check box "Include document being routed as an attachment in email assignment notification" needs to be changed to reflect the actual purpose of the check box.­ Ref SPR 1491463.­ Customers complain that the users are misunderstanding the purpose of it and expecting the pbo document as an email attachment when they receive the email notifications (­for tasks)­.­

Which makes it sounds like the purpose is not to include the document as an attachment.