> "root cause analysis", at least on complex systems, is a fools errand.

Not when properly understood--which, to be fair, it often isn't. The proper purpose of root cause analysis is to answer the question: does this failure mean I need to change something about this system? If the answer turns out to be yes, the thing that you need to change gets called the "root cause" of the failure. Of course that's a misnomer, strictly speaking, but that doesn't mean you answered the actual question wrong.

I don’t blame people for being confused about the term in software — it’s a bit more straightforward in manufacturing, for example.

That said, if you look at a system that failed and determine a root cause analysis is pointless, you may have just stumbled upon your root cause.