I read recently that Meta was trying to hire employees from OpenAI/Google/Anthropic for higher pay, and that they found that OpenAI employees were the most willing to jump ship. It's possible OpenAI is having an employee retention problem, and this is intended to keep employees and help attract new talent.
Keep employees in the short term. After 2 years, employees can retire comfortably. When the salary becomes irrelevant, you can hang around for more beach homes doing what the boss wants and keeping your work proprietary to the company, or quit and do whatever you want and do whatever you want with it.
Or maybe the golden handcuffs are heavier than what the article makes out.