Saving emails in the ‘Sent Folder’ of shared mailboxes

When composing a message from a shared mailbox, by default when the message is ‘sent’, it is copied to the Sent Items for the user composing the message and not the Sent Items folder on the shared mailbox. Well, conveniently there is a way to enable this option in Exchange 2016 and Office365.

I don’t understand why this option is not turned on by default because it accounts for a message sent from a shared mailbox yet there is no historical record of the message being sent from the mailbox. Apart from journaling if it is enabled or a third party software/ service.