Hmm... I don't doubt that this happened to you, or that it does happen often, but as someone who was in charge of a fairly successful online community with tens of thousands of community members and upwards of a million posts, I'm happy to say that I never went back. I did the same as moot in this situation - I prepped the people who I wanted to take over and made the transition slowly until I was doing almost nothing myself. Then one day I made a post and I was gone.

I didn't revoke my own access, though I doubt that I still have it (this was about 8 years ago). Even if I did have access, I certainly wouldn't want to go back and start changing things. I cared deeply about my members and fully trusted my administrative team to do what they thought was best, and sometimes that meant putting aside my own beliefs and trying something different.

It all depends on the person that's retiring, I suppose, but I wanted to offer something to counter your experiences.