I call this “isomorphic CI” — ie: as long as you set the correct env vars, it should run identically on GitHub actions, Jenkins, your local machine, a VM etc
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.
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.
I just did my own thing and wrapped everything deploy.sh and test.sh and when the shift to another system came... well it was still kind of annoying, but at least I wasn't recreating the whole thing.