Nope, I don't see your bewilderment.
1. "Golden Arch" is not a 30 year old musical term, it's a term which has been used for far longer.
2. Whichever of the terms used over the centuries to describe the idea/concept/theory you choose to use, the point is that it's not an absolute rule. Plenty of great art (inc. films) does not employ it, employing it certainly does not guarantee a great or financially successful film, especially as some of the data used in the article to prove the point was wildly inaccurate. My point was that while it's certainly no bad thing to know about the golden ratio/arch/spiral, it's also not an idea/theory/concept which is essential, as appears to be implied by the article.
There you go, it's really quite simple, nothing to bewilder yourself about!
G