While I do agree that the automation is what makes it best over others, an onion I have seen expressed online is how there is no encryption of the documents in server. I guess you can only use paperless-ngx to hold a bunch of documents on a small air-gapped device, much like storing hundreds or more papers in a box somewhere. Though in my personal onion, the files should be encrypted on the server if it's ever meant at all to be hosted on one.