It's important for the business that the insurance fund is safe. If you look closely you will find that it is unsafe. But if people believe it is safe you won't need the insurance fund, so do whatever you need to to inspire confidence in the insurance fund.

Oncall rotations are part of defense-in-depth against bugs and unforeseen circumstances: Most of the companies that survive without a formal one only do so by outsourcing this for the most common cases; to Cloudflare, to Amazon, etc. -- if there's an opportunity cost to being down someone needs to be able to pick up the phone when there's an outage or critical issue.

How does this situation improve in any way if X is a trade secret? Under what circumstance would company A be willing to accept payment to make X open, but not willing to license X as a protected patent?

It sounds like you'd be in exactly the same situation except that there would be a massive collective action problem trying to figure out how much the world should pay A to make the invention open and who should pay it, and also A and B would have multi-million-dollar incentives to engage in corporate espionage and counter-espionage that achieves no progress.

For example, suppose you started with a commit graph that looked like this:

    C1 --- C2 --- C3
     \      \      \
      T1     T2     T3
       \      \      \
        F1 - - F2 - - F3

    C1 --- C2'--- C3
     \      \      \
      T1     T2'    T3
       \      \      \
        F1 - - \  - - F3
                \
                 F2'

William Lin - https://www.youtube.com/channel/UCKuDLsO0Wwef53qdHPjbU2Q

Errichto - https://www.youtube.com/channel/UCBr_Fu6q9iHYQCh13jmpbrg

                    --> solve the problem
                  /
    see a problem
                  \
                    --> exploit the problem

That's not how git works. The commit contains the entire tree. You could prepare two separate repositories such that `git checkout deadbeef0001deadbeef` in one checks out the linux kernel and in the other checks out ILOVEYOU.exe.

Instead what you would do is attempt to make a file-object that has a certain SHA1 hash identifying it, and a colliding file-object that has the same SHA1 hash. Then you are free to give people who clone the repository different file contents depending on when/who/how someone requests it (if the file content is hosted on github, how to change the file object identified by a given SHA1 hash is an additional hurdle since it's assumed to be immutable and indefinitely cacheable; if you control the host yourself you can just change it whenever you like).

Phone numbers are nice because the marginal cost to a customer is low (they probably already have one) while the marginal cost to a bad actor is high (it's expensive to acquire many of them or to change one once it's been identified as malicious).

"I want to make a change to a shared library. Why can't I make a pull request?" "Wait, I have to use this unfamiliar interface to make comments on other people's changes and I can't leave comments on specific lines?" "You know, if you used Jenkins and Github then you could show the status of passing or failing tests right here on the code review screen..."

These social pressures are really quite strong. They affect a bunch of open source projects especially: people who want to make changes expect code to be on Github and might even mirror it there themselves (creating confusing situations for anyone trying to contribute). Even if the project does host its code on Github to allow for contributions from Github users, Github is (naturally) not very good about directing its users off of its platform to where the existing discussion and development is going on. "It's easier if you just do everything on Github" says Github, and their users by and large agree, and slowly more and more process (code review, merging patches, CI, documentation) gets sucked onto Github by the platform effect.

In the worst case, if someone notifies you of a configuration problem or some software bug that allows anonymous access to your database or the ability to remove logs, you may have to assume the entire database was compromised since the existence of that configuration issue or software bug.

Many games since (including Destiny) have tried to recreate that feeling of an oppressive enemy that you can't defeat, only push back or cut a temporary swathe through. But no one comes close to Halo.