It makes sense if you want to e-mail several files or a folder structure. You can attach a zip, but you can’t attach a folder.
And sometimes it just makes sense for the comprehension of the recipient. F.i. if I want to send an account statement and all invoices. Instead of sending 20 pdf files of which one is the account statement, I can actually send 1 account statement and 1 folder containing all 19 invoices.
If I want people to understand my reasoning, I’d better make it reasonable to them, right?