That's one part of it.

I can't speak for mike_d specifically, but there is a concern with having (potentially significant) modifications made to the codebase that aren't surfaced in the release notes. I imagine closed-source projects do this on a regular basis whether customers know (or care) or not.

The expectations for opensource projects are different though, particularly when it comes to system-level or near system-level components. So not being able to access the functionality is a great default but it doesn't address side effects of the changes or the desire to know about changes being made in our environments.