Git's selling point is that it's decentralized and distributed... but just look at the shitshow that happens whenever GitHub goes down. Git may allow for developers to all pull from each other, but in practice your employer will always have a canonical repo that's blessed as the official source, and if that one becomes unavailable for any reason work grinds to a halt. And that goes double if your company's deployment process is tied to GHA.
You’ve got workflows bolted on top that block forward progress when it goes down. Hooks for when push requests happen, when commits happen, etc. You’ve got code reviews in your workflow that cannot happen when the service is down.
Basically there is much more to a service like GitHub / gitlab than just “write code, commit”. These services enable powerful workflows. When those go down all you can do is write code locally. The rest of the pipeline is dead in the water, which in many cases makes your overall ability to work virtually impossible.
All the interesting stuff for normal people is built on top.
If it was a pure central authority + protocol you would be doomed to live and die with them. Imagine if instead of git + github you had some source code protocol that only allowed you to checkout the latest commit of some branch. All code history needed to be viewed by connecting to the central servers. Why not make it even worse, you could only view+edit a specific file of the latest commit on your machine. All other files must live on the central server, you are not allowed to build/compile code locally either... Centralization is the process of you giving up control to a "trusted" entity. If they fail you lose everything
Of course, if your build process is tied into github actions or something, that will still be broken. But that problem also exists for any other 3rd party build/deploy service you might use, independent of git-the-VCS-tool.
Yes, that's my point. It doesn't matter if your protocol is decentralized as long as your business processes rely on having a blessed authoritative repo, which most do. Yes, you can point your remotes somewhere else, but in practice nobody bothers.
I have worked on both sides of that.
Even banks are moving to SaaS first for their core applications.