Over 40 dev (Individual Contributor - IC as they call it) here and all I can say is that the article is completely ignoring large companies like FAANG, Microsoft, etc where ICs are allowed to remain ICs (design, write code, mentor juniors, etc) and they thrive given the right scope.
Edit: In fact these companies have a separate IC ladder to climb (if at all you wish to climb the ladder). If you're not interested in climbing the ladder, that's fine too as you can happily remain a strong productive engineer coding to your heart's content at a certain level (typically called the terminal/career level) without any pressure of moving up. I must say though that growth in the IC ladder is slower than the management ladder in most companies.