Huh. The standard 9mm Parabellum loads used to have about 350 ft/lbs of muzzle energy, or a bit more if you reduced bullet weight for increased velocity with the same chamber pressure. Now I see that loads that develop between 500 and 550 fl/lbs. At least one of these is identified as a "+P+" load, though:
https://en.wikipedia.org/wiki/9×19mm_Parabellum.
Similarly, 357 Magnum loads used to develop muzzle energy in the mid 500 ft/lbs. Now this can be pushed up to nearly 800:
https://en.wikipedia.org/wiki/.357_Magnum
There still seems to be a considerable difference between 9mm and 357 to me. It also seems like the actual difference would depend on how much you want to push the gun you fire the high-end rounds in for either cartridge. Both cartridges are offered in a wide range of guns, down to J-frame size 357's and PPK size 9mms, and the smaller gun is, the less I would want to push it really hard, if only for reasons of felt recoil. That would leave both guns firing ammo more like the old standards, where 357 Magnum had a distinct advantage.
As an aside, I also think that with everything thing else being at least similar (like bullet diameter), kinetic energy is a good measure of the potential of the bullet to do damage. The actual damage will vary with bullet design and with what is hit, and probably other things. (I hope I am not ignoring something important in the other things. Particularly something that is
not affected by kinetic energy. If I am, I would like to learn about it.)
To sum up: Yes, there is now 9mm Parabellum factory ammuntion that has about the same kinetic energy as the old factory standard 357 Magnum loads. However, a similar process of development has been applied to 357 Magnum, and there are now loads for it far more powerful than the old standards.
How that energy is translated into penetration in ballistic gel (which is what the Lucky Gunner articles are comparing) is not something I know about, but I would think that bullet design development would result in both cartridges using their kinetic energy as efficiently as possible. That would still leave 357 Magnum with a significant edge. On the other hand, I don't know much about modern pistol bullet design and construction, so perhaps there are limits to this of which I am unaware.
Maybe it could be said that the power levels available now in 357 Magnum are greater than can be used in a handgun of practical size, while that is not true of the new 9mm loads? Beats me. Between hearing about how 40 S&W is dying because it has too much recoil, and how 10mm is resurging because it is wonderful to shoot, I am very confused with that subject. I gave up arguing with people who like 44 Magnuim for self defense a long time ago.
PS - I used Wikipedia as a source because it is handy and has the kinetic energy numbers. For some reason Lucky Gunner, despite having both the mass and the velocity figures for every load tested, does not do this calculation. Has kinetic energy gone out of fashion? Maybe because bullet design makes so much difference now?
I know there have always been people who did not like KE, but they were usually fans of big slow heavy bullets. Have there been other changes?