I agree with the author's point about using popular tech stacks to alleviate the ramp-up time for new hire productivity, but that is not the optimal solution. The optimal solution is for management to not let high-productivity talent from leaving - increase their comp to whatever offers they might get in the open market. That's how labor economic works - it's a market. Investment bank and management consulting figure…
Except, in this case, the programmers in question had decades' worth of hard-won domain expertise that was absolutely critical to their job function. And, this product targeting a niche industry, it was relatively uncommon domain expertise. So much so that the only people on the job market who had it were these folks whom they were ousting. All of whom had found positions at competitors within a day or two.
So then the company lost their ability to maintain the product in any meaningful way, and, within a year or two, customers started moving on as well.