alt Hacker NewsI think you've got cause and effect backwards. Employers used to offer incentives to stay in a company and grow organically. They decided that was no longer going to be the deal. So they got the current system. There was never some sudden eureka moment when the secret engineers club decided they wanted to have a super stressful life event every few years just to keep up with inflation.
As I said in another response, I think (at least partly) a contributing factor was the essentially limitless salary budget that VC funded startups and the FAANG companies had. You had software developers who could suddenly make more than doctors and lawyers and of course many of them sensibly acted in their own best interest but that left other employers saying "we're not going to invest in employees who are only going to turn around and leave for salaries we can't pay" and "if we have to pay those kind of salaries, we're not going to hire junior people we want experience."