Fun to see DHH posting more on the SVN blog. He’s on a roll with posts I can’t resist quoting.
This is in part the tyranny of the 8-hour work day paradigm. When the work is progressing as planned and the core issues have been addressed, the right move for the manager is often to step back. But if all you know how do is “manage”, there’s no fallback. Nothing else to fill your time with.