> You can set up a backup Github?I can put a cloned backup of a git repository anywhere I want. (I do this with all my git repos; I certainly don't depend on Github--or Gitlab, or anyone else--to keep the only copies that aren't on my local machine.) I can't back up the other data that Github stores (issues, wiki, etc.), but that's because Github gives no way to download it, not because Github is "centralized". Github could provide the capability to download this data if it wanted to, without changing its underlying storage model at all. It just doesn't want to.
> when there is an issue with Github your team and deployment methods (CI/etc) would automatically switch to that backup
If what you are providing is "better failover performance than Github", that's fine (although I would want to see your actual uptime numbers before I'd believe any such claim), but that's not what "decentralized" means.
> I feel like I'm repeating myself, but the advantage is being distributed. Distributed systems usually aim to be resistant to these types of issues.
Sure, but unless you think Github literally stores all of their data on one single server machine, then Github itself is "distributed" in the same sense.
> I'm a bit confused at your question. Are you asking why being distributed is good?
No, I'm asking why you keep on saying "decentralized" when it turns out that what you mean is "distributed" (and when even "distributed" isn't the real issue--see below). They're not the same thing. You keep saying "decentralized is better than Github", but benefits like better failover performance come from being distributed, and Github is distributed, as I just pointed out above.
> you're asking why someone might not want centralization for the rest of the non-Git components[1]?
If your argument is "the rest of the non-Git components shouldn't be locked up in Github's data centers where nobody else can download them", that's fine, but it has nothing whatever to do with "decentralized" or even "distributed". You're just saying that all those other things should be in a freely accessible data store that can be cloned and replicated and accessed just like the git repo for the code itself. Sure, that's fine, I agree. But all this talk about "decentralized" has nothing to do with that point; it just obfuscates it.