You can mitigate the mass penalty by using bridling, no need for the flexible joint, Maybe the flexible joint is useful or harmful for other things, say varying the wing twist during flight, varying anhedral or dihedral, or smoothing or strengthening perturbations or oscillations. Or control.
Now it is scaling in number of wing sections rather than size.
I think this is similar to the segmented insect wings below. That looks better to me because you get to keep the efficient continuous wing, only now with each wing section being able to flex some. You can now also tune the width of the individual rigid wing sections and the flexibility of the joints. Maybe you want to keep the individual tails.