I think the point is that the only work that matters is work that will improve the customer experience in some way. That could be infrastructure/stability work, or that could be visible front-end work. Not sure how you're using the word "hidden", but that's my reading from this discussion. Either of those things are important/valued by management probably. But none of that should imply or require micromanagement in a high-trust engineering org.

Seriously, I feel you should write a blog post about this types of reporting strategies that describe the work that are both accurate and palatable to management (and perhaps most importantly avoid despise from other developers).