I would say that although the description of the technical issues is correct, the commentary is a little naive, and is clearly written by a non-photographer looking for conformation of the basic thesis.
First up, a very large about of photography is not portraiture. When I was seriously into film photography it was a given that you selected your film for purpose. And there were film stocks specifically intended for portraiture, and film stocks that were great for landscapes, action, studio work, and so on. It was well understood that you got sub-par results if your film was not best suited to purpose. Weddings were a big deal, and there was film that was really specifically good for that. But if you wanted vibrant colour, you have would not be using that film on people.
The cited article above notes that Kodachrome was not kind to black skin. It wasn’t kind to white either. But in different ways. It was a finicky film, but it was, in its day, the absolute best for vivid nature shots. Until the advent of digital pretty much all of National Geographic was shot on it. Especially Kodachrome 25, which was a harsh mistress, but could deliver in spades when you got it right. (What killed Kodachrome early was Fuji Velvia, which didn’t suffer from the same finickiness in exposure, and had luscious greens, and was an E-6 process, so could be processed by anyone.) Being a positive process, Kodachrome inherently was exacting, there was absolutely no wiggle room, and dark skin would have always been inherently difficult to manage. Getting any shadow detail with that film was always an uphill battle. I’m sure that if the technology existed, Kodak would have jumped on it to get that extra dynamic range.
The wide world of colour negative film got you just about anything you wanted. Kodak marketed half a dozen different films, all with different colour traits. But Kodak wasn’t the only game. Other big players like Agfa and Fuji, and a zillion smaller, also marketed their own. And they were all different.
The articles do get an critical part right. Film processes tend to be balanced to get the most obvious thing the right colour. Which is sometimes not what you think it is. Weddings, the thing that absolutely must be the right colour is the bride’s dress. Photographers would take samples of the material and balance the prints to ensure the dress was spot on. White dresses were easy, but all hell would break loose if the white dress had a hint of colour cast. But after this, clearly the skin colours should look reasonable, and here the predominance of white skinned subjects would have the a balance of the rendition favour such the the range of tones the average caucasian had, would render passably well. But it was amazing what you could get away with so long as the dresses came out right.
But there has been a long lived industry in make-up for photography, and it has always understood that what look good to the eye is not what looks good to the camera - and so make-up for portraiture has always compensated for colour rendition issues, no matter what the skin colour of the subject. The examples of poor colour rendition of black actors in movies suggests a level of incompetence/indifference in the makeup department of Hollywood to the requirements of black skin as much as it does the film stock maker.
Colour rendering is a horridly difficult art. Even with modern digital cameras there is a huge set of compromises made, and no matter what is photographed there will be problems rendering accurate (or even acceptable) colours of some elements in the final result.
The first time I saw a multi-racial “Shirley” test photo my reaction was “really? - You think your film is good enough to manage that?” No doubt, if everyone had dark skin, the film manufactures would have worked harder and earlier to improve the process. Because they were catering to a perceived market of whites they stopped earlier, because fair skin is technically much easier to get right.