The more stable/secure a monopoly is in its position the less incentive it has to deliver high quality services.
If a company can build a monopoly (or oligopoly) in multiple markets, it can then use these monopolies to build stability for them all. For example, Google uses ads on the Google Search homepage to build a browser near-monopoly and uses Chrome to push people to use Google Search homepage. Both markets have to be attacked simultaneously by competitors to have a fighting chance.
It does? Do you know git is a dvcs? And therefore you're able to continue working without an internet connection or a service provider being up? It delays the code review process but doesn't break it.
I get it that you want it to be 100% up, but let's be serious your FLOSS projects probably break more stuff than GitHub being down does.
If a company can build a monopoly (or oligopoly) in multiple markets, it can then use these monopolies to build stability for them all. For example, Google uses ads on the Google Search homepage to build a browser near-monopoly and uses Chrome to push people to use Google Search homepage. Both markets have to be attacked simultaneously by competitors to have a fighting chance.