There’s no empirical basis for the mystical claims about the golden ratio, and most of the examples from ancient buildings, famous artworks, attractive people’s faces, and so on are a result of selecting examples which match the pattern while ignoring those which don’t – yay numerology!
It just happens to be a fairly reasonable ratio for a lot of purposes (and happens to be the ratio ϕ = a/b such that ϕ = a/b = (a + b)/a), and sometimes therefore an easy rule-of-thumb. Use it or don’t use it. You won’t be missing some secret of the universe.
Not for the ones typically cited, such as Leonardo’s work, or the Parthenon, they didn’t. Some artists certainly did. Le Corbusier (architect) based a lot of his designs on it, for example, as did Jan Tschichold (typographer).
Anyway, they weren’t working from anything empirical, but from their own mystical preferences.
It just happens to be a fairly reasonable ratio for a lot of purposes (and happens to be the ratio ϕ = a/b such that ϕ = a/b = (a + b)/a), and sometimes therefore an easy rule-of-thumb. Use it or don’t use it. You won’t be missing some secret of the universe.