Coming from a Linux background, I'm used to a file having an owner, and a owning group. Access permissions can be set separately for owner, group, and others, and that's it.
Now on (NT-based) Windows, it's a bit different, because Windows uses ACLs. That means instead of having three lists of permissions (owner, group, rest), I can have as many lists of permissions as I want.
So far, this makes sense. However, why does Windows still have the notion of a file owner? To me it seems that with ACLs, a "file owner" is no longer needed, because all access can be configured via ACLs.
So why does modern Windows still use file ownership? Where does it make a difference who owns a file? As long as two files have the same ACLs, file ownership should not matter - or does it?