Thank you for the your feedback! It's very important for a tool like this to be clear and transparent about what it's doing. The docs definitely need to be improved. It's already a lot for some info to be lost and not enough, at the same time, in other areas.

By the way, if you don't feel comfortable with the minification functionality you can still use docker-slim as a Docker image inspection and profiling tool (take a look at the report files it generates). Additional package level reporting is on the todo list. Image and Dockerfile linting functionality is coming soon too.