If you try to change jobs every 2 years and are not great at your current position, you'll likely be sorely disappointed.
As you say Joe Dev wasn't good enough at their job for anyone to work to keep them, but somehow they have to be excellent to land a job somewhere else every 2 years. My point is Joe Dev is excellent at something, but that is interviewing. It says nothing about his actual job skills except that they aren't so great as to have a company bend over backwards to keep him.
If you try to change jobs every 2 years and are not great at your current position, you'll likely be sorely disappointed.
As you say Joe Dev wasn't good enough at their job for anyone to work to keep them, but somehow they have to be excellent to land a job somewhere else every 2 years. My point is Joe Dev is excellent at something, but that is interviewing. It says nothing about his actual job skills except that they aren't so great as to have a company bend over backwards to keep him.