Now say you're a medium sized hyper-growth company in a competitive space. Does spending 10 times more and waiting 5 times longer for redundancy make business sense? You could argue that it'd be irresponsible to over-engineer the system in this case, since you delay getting your product out and potentially lose $ and ground to competitors.
I don't think a black and white "yes, you should be punished" view is productive here.
If its standard CPU that everybody else uses, and its not known to be bad then no.
Same for software. Is it ok to have dependency on AWS services ? Their history shows yes. Dependency on brand new SaaS product ? Nothing mission critical.
Or npm/crates/pip packages. Packages that have been around and seedily maintained for few years, have active users, are worth checking out. Some random project from single developer ? Consider vendoring (and owning if necessary ) it.
That doesn't extend to ridiculous lengths but as a rule you should engineer around any single point of failure.
Yes
> Did I lack due diligence in choosing to accept the risk that the other team couldn't deliver?
Yes