> I don't care if everything fails sometimes

You can say you don't care for reality, but it's not going to help you have better systems.

> There are sites that should NOT go down

Then they surely either engineered their system to not 100% rely on Fastly or negotiated appropriate terms with Fastly (Or decided Fastly going down was an acceptable business risk, which it is for nearly everybody). Everything else would be negligent, and surely nobody would be negligent when operating a site that "should NOT go down"?

> You've just witnessed almost the entire internet break because of a catastrophic cascading outage that affected lots of huge companies, since third party services used and trusted Fastly.

Blame the companies that relied on Fastly being up 100% of the time, even though Fastly explicitly states that they might be down any number of hours, and they will even give you money back for that [1]. If they did offer 100% SLA, it would probably be out of budget for most users, as that kind of systems are prohibitively expensive to run.

Depending on a single CDN like Fastly is building an SPOF into your product. It is not less of a design blunder that whatever Fastly did internally to have an outage. If Shopify lost millions because of a short, simple third-party outage they have at least as much of a high-priority postmortem to write and issues to address as Fastly.

[1] - https://docs.fastly.com/products/service-availability-sla