> don't you think it's highly unlikely that someone will stumble over the power cable in a hosted datacenter like hetzner?

You're not getting the point. The point is that if you use a single node to host your whole web app, you are creating a system where many failure modes, which otherwise could not even be an issue, can easily trigger high-severity outages.

> and even if, you could just run a provisioned secondary server (...)

Congratulations, you are no longer using "one big server", thus defeating the whole purpose behind this approach and learning the lesson that everyone doing cloud engineering work is already well aware.

Do you actually think dead simple failover is comparable to elastic kubernetes whatever?