There's no way of knowing if in the interim 20 years the management changed entirely and also their pay strategy.
So tracking their fortunes over 20 years probably doesn't tell us a whole lot, without that knowledge.
But there are plenty of more recent studies which back up aspects of that article. Such as performance related pay targeted at individuals not necessarily being a good thing.
We have it at work and honestly everyone thinks it's a farce. Nobody believes it works.
The principle of the article I linked was that often people have a too-simplistic idea that squeezing wages is always a good thing and to be successful you have to pay your staff as little as humanly possible.
I would hope that there are some companies out there that don't adhere to that goal/principle.
e: Tbh so many factors can change over 20 years that to say the pay strategy was the determining factor in their decline is a bit ludicrous tbh. Almost anything could have happened to those businesses resulting in their decline, completely unrelated to their pay structure.
Perhaps what they were offering simply didn't keep pace with changing consumer demand. That would have nothing to do with pay structure.
e2: The keep take away from that article is that - at the time - they were offering better pay structures than their competitors and also performing better. Thus proving that you don't have to squeeze your employees as hard as possible, in an effort to keep wages as low as possible.
You can if you're inclined to treat your employees as disposable worker bees, but you don't have to.
You are probably conversing with someone I have on the ignore list but I agree, paying a good salary is important and in the long term beneficial to the company. This is exactly why salaries are not fixed for the same role, because people's individual value of a salary is different.
Also, paying higher salaries has a bigger positive impact at the low end rather than the high end. Paying employees higher salaries in the range of minimum age to national median typically sees large increases in productivity, reduced sick time, increased loyalty etc. As salaries get higher then people start to consider more and more other variables with increasing weight: commute time, office hours, responsibility, career growth opertunity, respect, flexible hours, remote working etc. There are a lot of things companies can do without a direct cost and these things have the same benefits of improving productivity and loyalty.
This is made very evident looking at productivity between the UK and say Germany. Germany works lower annual hours with shorter work weeks and more holidays, but the productivity is higher.
If a company is offering a good work environment then the employees look at aspects well beyond salary and a natural occurrence will be greater salary variances. Some employees may have negotiated a higher salary, perhaps because they have a higher living cost with their kids, other will be perfectly happy ona lower salary and enjoy the benefits of the company.
Companies with a horrible work environment where the employees despise being their and only turn up to get their paycheck each month will be filled with jealous workers being bitter over pay differences.