(First I should say that I do have a habit of including background information that is clearly already known to some readers, just in case some other reader of the post is not aware of it.)
I did find one thread from two years ago on the exact same subject:
http://yabb.jriver.com/interact/index.php?topic=62458.0which was somewhat helpful in clarifying the state of affairs.
I then did some experiments with Panes, and discovered that MC is mostly independent of any pre-existing grouping of files (outside of the default Genre-Artist-Album setup). This has some clear advantages in allowing users to highly customize.
For example, in one case I had two different copies of an album in two folders, identically tagged, and using default Panes view, a right-click Play of the Album would play both track ones followed by both track twos.
But if I changed the right category to "Year-Album", since one of the copies was incorrectly tagged as having year "2012", then the right category would separate the two copies as "1965 - [album name]" and "2012 - [album name]" and thus right-click Play would only play one copy at a time.
So, now I am seeing where you are going, when you mention filepath or filename - creating a right category that is forced to be only one folder.
However, I think that MC should have some (optional) recognition that all audio files in a folder are a group. Since MC includes CD ripping capability, it recognizes a CD concept (as opposed to just independent "songs"). (In fact, earlier in the thread, when I was referring to "album", I'm really more referring to "CD" or at least a grouped release of tracks.)
Currently, when a category is selected like Genre or Artist, if there are multiple albums, it lists them separately in the File List. But when an Album is selected, it puts multiple versions of the same album together as one album, again with all the Track Ones first, followed by all the Track Twos, etc.
So, on the one hand, MC is treating all categories as equally able to be listed and played, but on the other hand, it is not recognizing "Album" as also able to have multiple sub-entities, even though it allows Artist and Genre to have multiple sub-entities in the File List.
If my hypothetical "Group all audio files in a folder" option were ticked, then the File List would show - for example - each separate version of "Kind of Blue by Miles Davis" - the same way it currently shows separate albums in the File List if you select Artist "Miles Davis". (Lacking any other input, the folder name could be shown to differentiate the different versions.)
(By the way, in the File List, there is currently no way to play one of the listed albums by itself, something which prompted the original post in the thread.)