Thanks for pointing this out, I've never heard the 5Y before:
https://www.mindtools.com/a3mi00v/5-whys
5-whys is a linked list. Sometimes, things don't have a single cause. One mental model I find useful, while harder to apply, is to see things as a web of dependency. What are the whys for this layer of problem. What other problems are also implicated by the "why". i.e. A graph
It’s a pretty useful way of representing things (although I personally prefer indented bullet points).
But notice that they don't fit the GP's explanation at all. As strange as that may sound, causality is not unidirectional in a complex system. You are losing data by coercing it into that, and that data is quite often relevant to how you fix a problem, even if it's not commonly relevant for identifying the problem.
For example, given a wet floor, 5-why tends to give a single reason, e.g. because it rained, and people may drill deeper into why it rained. My intention was to search broadly, i.e. what could also cause wet floor, the weather, a burst pipe, a road cleaning truck, a nearby fire, etc, and also to search adjacently, e.g. water outage due to burst pipe, flooding due to rain, etc. This will quickly expand the searching surface.
It helped me to see the river instead of flowing downstream. e.g. Engineers was drowning in "tasks", it is not uncommon to have solutions along the line of work harder, pay down tech debt and hire more within the engineering org. But upon searching, the cause might be anywhere between lacking product market fit, broken and interdependent processes, fragmented and over specialised teams and tooling, and religious pursuit of growth, which has nothing to do with engineering in a traditional sense.
That being said, you always have to avoid fooling yourself when building logic diagrams. It's easy to do.