Earlier quoted context omitted.
Unless you have a lot of flexibility in terms of where you work, this type of advice is becoming less relevant in an IT job market that's in free fall. Much fewer devs can just jump ship at will than between 2003 - 2022.
The market is not in a free fall. Or rather, it's only a free fall for junior fresh-out-of-college developers. If you are skilled and senior, don't believe this nonsense and have confidence in yourself. This is just an extension of the imposter syndrome that I see often in many people.
The entry level market is getting more and more over saturated. It is bleeding upwards to mid level slowly. But if you are a skilled senior you are still in high demand. If not your resume probably sucks or you are not as skilled as most seniors.