let me explain it as a user story.
As a writer of E-Mails I would like to add one to many attachments from a prepared static list of selected files or folder in PPT, DOC, PDF to respond to inquiries e.g. for specific information.
I would like to add these attachments with minimum effort.
The benefit is that I do not need to search local file structure and cloud storage like OneDrive each and every time.