A simple sales pitch will be:
"Go to a sales order and get the attachments for all items on the sales lines"
Like building: SalesTable --> SalesLine --> InventTable --> EcoResProduct

Or:
"Go to a project and check out all the documents attached to activities".
"Go to a sales order and find all the certificates attached to the serial numbers when the product was produced or from a purchase order receipt"

FinOps only has ONE metadata for a document, but you actually don't need more just a faster way to find the related data!

You would need to be able to create these aggregated channels yourself and have different views.
Using relational document aggregation is an awesome way to quickly get to the documents needed. It reduces the requirement for metadata "over tagging". Meaning the document doesn't have to be attached to all the metadata, but only the core record like today. Using the relationships between the data that is created through operational processes you will be able to aggregate documents.

This is somewhat used in Production with Document groups, but is only locked into ONE scenario. Build something you can mold into whatever you like.