especially when the authorities stretch back for hundreds or even thousands of years, with no refutation that anyone has mentioned.
But you've mistated the claims.
No one has claimed, not even the Greeks, that phi was a ratio found in all human beings. They simply asserted that it was the ratio found in
ideal humam beings, without asserting that that ideal existed in anything but their statuary.
So your "authorities" don't even support your claims. No one but you has claimed that phi is found in all humans; the existence of humans in whom that ratio is not found proves you wrong. (It's called a "counterexample." You might look it up if you're unclear on the term. Counterexamples disprove arguments, even those from authority.)