I understand that metadata-driven views is a better way to organize files than folders. However, in my library, all the team members should be able to view all docs, but the document 'owner' alone should be able to edit, create his doc, or upload his doc. With folders this is easy: provide folder level permissions as desired, these permissions get inherited from folder level to doc level automatically. In a folder-less flat list of docs, I can create a metadata/column called 'Owner' (of type person/group), but how do I give different permissions to that owner? I have read about using workflows for this, but I am looking for a method as simple as folders. If I can beat the convenience of folders in this sense, then I can banish folders for ever! Thanks for any suggestions in advance.
Unique permissions at item level can become very messy and difficult to manage over time. This becomes particularly difficult if you have hundreds or even thousands of documents with unique permissions and then need to remove a user's permissions.
Your solution of using folders, may actually be better for permissions management (a folder for all the documents a user owns).
You could use metadata for your documents while also using folders to manage permissions. This would ensure that you retain important information through the use of metadata and make your documents easier to find via search. You can also create flat views which filter using the metadata applied to documents.
If you want to keep your document library organized in the long term, one idea is to not give users Edit permission or above at root level. Manually create individual folders for each user, then give them Edit permission only in that folder.
To automate the process of assigning unique permissions, you can use Flow with Call REST API action.
Here are a few links for your reference: