It is true. Your premise involves covering distance, if you don't need to do that, the lesser resistance on a shorter fin will cause you to expend less energy. I thought this was common knowledge.
Agree that different fins has different applications. For example, it is not practical using free diving fins for wreck penetration or cave diving. For these applications, better use jet fins, Mares Quattro or other fins alike. For mud diving with no current and not requiring covering distance, the short fins are less troublesome.
However, for most of the recreational diving situation in particular in handling current, covering distance or saving energy or crusing the reef, free diving fins are the way to go.
Not discussing physics or fluid mechanics as it is far more complicated to explain though I am a mechanical engineer by training, just want to share my real life experience.
I used to use Mares Quadro (have considered between the Jet and the Quadro and finally chose the quadro because it may be better for flutter kick). In a Maldive Liveaboard trip when I was handling current, finning my Quadro crazily, I hardly moved a few meters to get on the rock for anchoring. After that, I started evaluating my trusted Quadro fins and searched for fins more suitable for handling current. Then ....the long free divining fins came to my mind. Initially, I was curious if I could handle this type of fins and concerned about if it need extra efforts for using it. Finally, I gave it a try.
On boy! The long free diving fins are so much more powerful and so much more efficient compared with my Mares Quadro. Also, they handle all sort of kicking well. Flutter kick, frog kick, helicopter finning, backward kick, scissor kick.....etc, they handle as good as my Mares Quadro if not better. Even frog kicks are much more powerful. The only difference is that they are longer and is not suitable for diving in places where space is limited such as wreck, cave...etc.
For handling current, no contest. They are so much more powerful. When other divers using short scuba fins finning like crazy moving against current, I just do normal finning and could follow closely to the DM who has been finning crazily against current using normal scuba fins. In term of efficiency, they are a lot better, For reef crusing without strong current, you can use leisure frog kick (which I think is not a very efficient type of kick for propulsion), or even better, very small flutter kick. Just move your ankle using very small amplitude flutter kick and you get good propulsion with very little effort. These are my real life experience. No need for long long debate in physics/fluid mechanics....etc. I now use much less air compared with the dates when I was using Mares Quadro under similar conditions.
Of course, if the trimming is not proper the finning techniques are wrong, the results may be very different. For an improper trimmed diver inclined 45 deg at the propulsion direction, the longer fins may result in larger cross section area against the flow meaning more drags. Improper flutter kicks such as bicycle type finning may not see the benefit of long fins.
For materials, I still think plastic long fins with the appropriate stiffness is more appropriate than fibre glass or carbon fins for scuba diving. The difference in efficiency may be minimal but plastic fins are a lot cheaper and far more durable when you consider how the crews handle your fins.