And yet, you would be surprised at the amount of people who react like that's an ignorant statement ("not feasible in real world conditions"), an utopic goal ("too much time to implement"), an impossible feat ("automation difficults human oversight"), or, my favorite, the "this is beneath us" excuse ("see, we are special and this wouldn't work here").
Automation renders knowledge into a set of executable steps, which is much better than rendering knowledge into documentation, or leaving it to rot in people's minds. Compiling all rendered knowledge into a single step is the easiest way to ensure all elements around the build and deployment lifecycle work in unison and are guarded around failures.
Building a Github-specific CI pipeline similarly transfer it into a set of executable steps.
The only difference is that you are now tied to a vendor for executing that logic, and the issue is really that this tooling is proprietary software (otherwise, you could just take their theoretical open source runner system and run it locally).
To me, this is mostly a question of using non-open-source development tools or not.
Automation renders knowledge into a set of executable steps, which is much better than rendering knowledge into documentation, or leaving it to rot in people's minds. Compiling all rendered knowledge into a single step is the easiest way to ensure all elements around the build and deployment lifecycle work in unison and are guarded around failures.