The truth is hidden in a comment: The goal was to learn fanotify syscall using a real world use-case. This said, when Dockerizing an application from scratch, using an optimized base image may be a suitable option. But that's not always the case. For instance, I often start a project from the Python base image which contains loads of generic libraries that I will not use in a given project but will be important for others. This is when a profiling based approach is interesting. You get the ease of a known environment and the efficiency of an optimized image.

OSv is a unikernel and isn't a container... but anyway, good point!