Well, sort of. The whole big ring thing got dropped in favor of VT2+ intervals. Which do work of course. However, these studies show that doing them at low cadence for a few weeks works even better. Note that in at least one of these studies, and recommended by Carmichael, is to do some plyo first, then go out and hit the low cadence work on the bike.
So an interesting thing is: what's going on physiologically with these high pedal force intervals? Is it increased muscle fiber recruitment? Different fiber type? Changing IIa to IIb?
Understanding Muscle Fiber Type
Whatever it is, this is indeed leg strength work. If you can push on the pedals harder, your legs are stronger. There are many drills to increase pedal force. One of the commonest is to do big ring standing starts, going from say 10 mph in your sprint gear to on top of the gear with 5 minutes recovery between or going from very slow and only doing 10 pedal strokes, similar recovery.
Plyo increases pedal force, as do squats and then jump squats.
Be all that as it may, nothing increases speed like anaerobic intervals, as you point out. Leg strength, however, is still a factor. You simply have more endurance when you use a smaller proportion of the available contractive force in your legs, back, abs, arms, etc. By analogy, you'd be able to hike fast uphill for a lot longer if you can squat your bodyweight than if you can only squat half your bodyweight. One steps up one leg at a time. I would think that would be obvious.
Personally, I have seen big changes in my high end performance by doing leg strength work: going from getting dropped to leading on hills. No change in interval protocols.