Why I move from docker for selfhosted stuff was the lack of documentation and very complicated dockerfiles with various shell scripts services config. Sometimes it feels like reading autoconf generated files. I much prefer to learn whatever packaging method of the OS and build the thing myself.
Posix is the standard.
Docker is a tool on top of that layer. Absolutely nothing wrong with it!
But you need to document towards the lower layers. What libraries are used and how they're interconnected.
Posix gives you that common ground.
I will never ask for people not to supply Docker files. But to be it feels the same if a project just released an apt package and nothing else.
The manual steps need to be documented. Not for regular users but for those porting to other systems.
I do not like black boxes.