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…
Also, it's much more difficult to quantify the impact of a software engineer compared to investment bankers and consultants. The latter two are directly making money for the firm.