Very good point. When I was a developer myself, I implemented that philosophy by making sure that whatever knowledge or expertise I had, which distinguished me from the other developers in my team was shared and distributed to my colleagues.

So - in stead of making myself redundant, I endeavored made myself replaceable.

Note: Though, the only time I worked as a developer, I was more experienced and knowledgeable than my team members (very junior team); I was never a great or experienced developer. In retrospect, I probably wasn't even a good developer.