You're missing the point, Frankie-boy.
The point being that "all-women shortlists" do the central party several favours and aren't at all arbitrary:
1) They disempower constituencies from one of the few remaining things they're permitted - selection.
2) They allow the party as a whole to look as if they're "challenging sexism" (although all they're actually doing is window-dressing).
3) They permit the insertion of "on-message" candidates into safe seats, "locking in" the loyalty of those candidates to the party heirarchy, and not the constituency party.
Of course it's not designed to work. Not for the constituencies, anyway. But what do you expect? Labour has been gutting constituency parties of power for 20 years now!