Probably because deployment is environment specific? So I guess that would be ok for your own project, but not something intended to be shared, where you don't know the target deployment environment.
Because deployment tends to be very context-sensitive[1], but code should almost never be.
[1] Are you running this in the cloud? On Google? On AWS? Cloud functions? A containerized VM? Maybe you're running it on an old Mac in your basement. If you're deploying on Linux, you're using lots of bash scripts but -- whoopsie -- those won't work on Windows.
[1] You've basically listed the very reason I'm using docker. It makes my code deployment agnostic. Bash "setup" files? been there. I write Dockerfiles.
I think that's the only thing I'm strongly opinionated about as a developer.
--- EDIT
This is a classic. Reading the backend "how to run" guide I see:
This should settle any debate about docker being "overkill". Developers are notoriously reluctant to install things on their dev machines. As-is this repo has non-trivial setup friction which will reduce # of potential users/testers.
Like I mentioned, I have laptops that can't even run Docker. I've had to fix CMOS/BIOS settings to be able to run Docker on my main dev box. Also, running Docker can sometimes mean not being able to run VMWare (due to virtualization settings). Not to mention that version controlling Docker repos is a huge pain in the butt, we've had to call our dev ops guy in the middle of the night because some random dependency changed some version that broke something down the line.
Pretending that using Docker is as easy as "docker-compose up" is either disingenuous, or you simply haven't used Docker as much as I have. Either way, I still contend that Dockerfiles have no room in a source code repository.
This is why Docker is suggested. It is the best thing so far even though a more polished system can/should take its place.
A well written Dockerfile and docker-compose files contain and describe all the dependencies you need and you can copy them to an Ansible playbook or just a script for your choice of OS/environment.
Why?