Can you fire 80% of doctors and a hospital will survive? Probably, the janitorial staff will still come in, and the light switch will still light a bulb. As a sibling comment notes, the degree to which employees are expendable and measure of survivability is key. Business types will erroneously think they can fire 80% of the staff, keep the lights on, and keep up new feature development. The biggest risk with this sort of minimizing thinking is thinking you can achieve more with less: you often can't, especially when it comes to the large business environments this article specifically carves out (the concept does not apply to small and medium sized businesses).

Growth often comes with dead weight. You can't 10x your staff overnight and expect the same output per engineer. And as you grow, your organizational structure impacts your architecture (Conway's law). The downsizing frequently is an unwinnable scenario, and people need to recognize that going into it.