I've read through this but I'm not sure I'm seeing any advantages to Buildpack.

First point - I see an example of a Dockerfile in TFA, but when it comes to the example of a Buildpack there isn't one; I just see a conceptual description of an abstraction. It appears that a lot of the inference is hidden away by use of 'detection' but is there magic hidden underneath? Does it allow arbitrary hacky steps if needed, like adding a random certificate?

Second point - A Dockerfile explicitly codifies what's happening. I can look at it and know how the build will go or what I need to change. The Buildpack equivalent would be spread across many different files, does that sound about right?