You should be mad at the Capitalists not the workers.
This is one of many ways that folks aged 70+ had it much better than folks in the workforce now, and represents generational inequality that you should not minimize or attribute to "capitalists."
You may, if you like, attribute it to "generosity" by individuals indifferent to "math."
Shouldn't a reasonable business have been investing forward to avoid this problem? IE, you don't use todays dollars, you use yesterdays dollars.
Its seems the flaw is that they lacked sufficient savvy to invest the pensions in a way where it would be able to build upon itself.
Then, a competitor disrupts your segment. The competitor is new, and for whatever reason does not have the same legacy pension expense. In order to compete, you must invest. But your pension expense in particular does not allow this.
What does the legacy enterprise do in this situation? In many cases in the 20th century, per Patrick, the business lost relevancy and slowly went bankrupt.