Hardware misconfiguration does not allow CRS to start up

Sometimes the most straightforward MOS articles can tell you so much, and the article "CRS is not starting up when Private Interconnect is disconnected on the other RAC node" from note ID 1981887.1 is a great example of that because there is such a simple explanation at the heart of this article even though it teaches so much.  Did you see this answer coming?  Does it make you rethink anything you have done lately?