I third this opinion: another reason it’s important is it allows you to do your build in an emergency when CI is down for whatever reason.

CI automation is for me the thing that replaces me running scripts one by one (and reporting/deploying results)

It is not the thing that does the building/testing/deploying. That’s the scripts that are hopefully written in a debuggable, portable, language.

This is a really good point. Most of my deploys go via GitHub Actions these days and it's not easy for me to deploy manually should I need to when Actions is unavailable - I should fix that!

Like aviation, every regulation/rule is written in blood ;)

This is why the three of us should record a podcast episode talking about this in the context of the points made in the Ironies of Automation

https://en.wikipedia.org/wiki/Ironies_of_Automation

Agreed - I had to switch from TeamCity to GitLab earlier this year and I was very glad that all of pipelines were single-line calls to shell scripts.

Indeed, to rely on third party actions in a closed runner ecosystem, is simply unwise.