While similar looking, 1...Nc6 breaks a fairly general principle of blocking black's c-pawn (which plays the thematic break move of c5) in a 1.d4 type of opening.
With the Alekhine, you don't commit to something like the above that early so I believe that is more flexible than this one.
Of course, Masters have played a few games with this but I'd dare to say it is "equal" (if you can ever call openings EQUAL! :)) to the Alekhine's.
Another reason for the lack of popularity of this move is that it's very unforcing. Here the d pawn is not really threatened, so white might play also 2.e4 (trasposing to a nimzowitsch defence) or 2.c4 with a trasposition to a more mainstream 1.d4 defence such as the chigorin QG; that's quite a lot of stuff to learn just to make 1...Nc6 work. And even if you like these defences, it still makes little sense to start with 1.d4 Nc6 instead of 1.d4 d5 2.c4 Nc6, since it just gives white an extra good option (2.d5) wothout gaining anything.
Lundin mekvitz opening is here as follows: 1.d4 Nc6 2. d5 Ne5.. and so follows with white gaining tempo on black knight like in alekhine defense. With that in mind, it seems as if Lundin mekvitz opening is reflection of Alekhine defense in that respect are both equally good hypermodern defenses?