Network storage does not handle the online/offline switching as transparently as OneDrive (or other cloud storage).

For large enterprises that old architecture you refer to means long lead times on network and storage outage notifications, and huge fallout if an outage window is blown.

And if the building network goes down, or if your storage servers are located off site because you’re too big for one building and the commercial internet goes down, etc etc

But it doesn’t have to be OneDrive. There are many other options. I run ownCloud 10 for my personal files. If I were a small to medium business, I would look hard at OCIS.