I don't understand the PID1 case. You are running a single process, why do you have to collect zombies?
In fact, I understand none of these points. This seems all very hard to relate to. These are containers and not VMs. Most of that stuff should run in a separate container.
Your single process might spawn child processes that double fork, resulting in zombies. Unless you've read every source code single line in the app, plus every single source code line in all its dependencies (and all dependencies of all dependencies), you really can't be sure that that won't happen. And when it does happen, your system is not behaving correctly.
And what if your single process spawns a child process that encounters an error, and logs only to syslog? If your syslog daemon is not running, you will never know that there has been an error. Again, if you've read every single line and know that this does not happen, then that's fine. But the point of baseimage-docker is to provide a good and safe default so that these edge cases are already taken care of for you.
In fact, I understand none of these points. This seems all very hard to relate to. These are containers and not VMs. Most of that stuff should run in a separate container.