I started as a dev many years ago, then moved into sysadmin / devops stuff for over a decade, and then moved back to more hands on dev stuff again a few years ago. I think your statement that "those things don't require "special" skills other than docker/ansible knowledge" is over-simplifying things a bit.

Writing a production quality Dockerfile or Ansible Playbook requires more than just a bunch of "apt-get install" statements. You need a bunch of knowledge about how each bit of software should be configured and tuned for each individual use-case.

Once it's been written, then the devs can happily automate all the things as much as they like. Writing it in the first place is where a lot of what was traditionally sysadmin knowledge comes into play.

Anyone with a bit of patience and practice can follow a recipe in a cook-book. Not everyone can write one.