With all due respect to the late, and usually great Sheldon Brown, his article spends a lot of time talking about the things that matter while addressing the issue only obliquely. Mafac cantilevers are the type he calls wide-angle. That's the one on the right in this pic:


Though he identifies types by what he calls cantilever angle, that doesn't really affect the performance directly. The arm is one rigid piece so it could have any arbitrary shape. The key property is how much torque the cable can apply to the arm, and that depends on the tension in the cable and the angle a. The closer a is to 90deg, the more torque you get and thus the more force of the pad against the rim.

Centerpull brakes get more power with a shorter cable by having more tension due to a greater mechanical advantage. Sheldon Brown describes this correctly. It is determined by "how straight" the straddle cable is, i.e. by the angle at which the two sides comes off each other at the yoke. With a centerpull, angle a doesn't get small enough to offset the increased tension from greater mechanical advantage.

But with the cantilever shown on the right a short enough cable can make the angle such that it pulls at 0 deg, directly into the arm, thus giving no torque at all. In fact, if you make it so short that it runs directly over to the other side in a line below the pivots, then it will pull the arm away from the rim!

A year or two ago I did a complete mathematical analysis of the tensions and torques due to these different angles, specifically the angle a and the angle of the straddle cable from the center to each side. I posted the results here in C&V but it's probably lost in the depths of dead threads. Anyway, one key conclusion is that when the end of the straddle cable is below the arm pivot as shown on the right above, there is no way you can get angle a near 90deg, and the torque lost from that effect will be greater than any increase in mechanical advantage you can get with a shorter cable. Inotherwords, a longer cable is better for that kind of brake.