Instead the article read to me as if the benefit of displaying this message is that the user's frustration might be allowed to shift to the sub-contracted vendor. I find it hard not to be infuriated by that idea.
And yeah, I think it means it's the most highly rated... or at least something very close to that.
Unless the error message is a slightly-less-functional app, no.
OP was playing the role of the user. Paying customers don't care about the implementation details of the products they pay for. They only care about whether or not they work.
The hard fact is that /your app is unavailable/ and I promise that >99% of users won't care why. Did anyone care why Twitter used to Failwhale? It was down, and that sucked, and software exists these days (and has for >20 years) to eliminate single point of failure.
And in practical terms, it seems totally theoretical.
In my experience, more information is always valuable. It's not a matter of shifting responsibility, it's a matter of understanding what the problem is and efficiently getting it resolved.
Sending out an error that is incorrect is wrong -- both a theoretical and practical observation.