It varies with the company you are at... but building pipelines is just one of the ops tasks typically. Ie, in your gitlab-ci.yaml example, ops would have given you the template (assuming you were going to be the one committing it) that your pipeline had to follow - so it was uniform with the thousands of other pipelines in the company. It's unusual at most of the shops I've been at for devs to ever build their own deployment pipelines. That might be OK at a smaller shop, but once you have 100+ deployments of any type, the devs have lacked ability to keep it all uniform at scale.

A better way to put it... most of my colleagues in an Ops roles already did development for 10-15 years, and moved on to developing the tools to deploy other people's products. Additionally, kubernetes isn't everywhere - they also build pipelines that produce AMI's, GCP images, and write the terraform/cloudformation/HEAT/etc to deploy those things. If you wonder "who automated blue/green deployments?", that's your ops team.

Also, in your example of "human kubernetes" - ops builds those clusters, and monitors those node pools. If you half less than a dozen clusters, or less than 100 nodes among the pools - you might not even have an ops team.