You're absolutely right, though this argument can be used against literally any finding in any field. I agree the evidence is somewhere between minimal to non-existent I'm just pointing out that calling people complete idiots for thinking there's something there is harsh. It's not obviously false on the level of flat earth or astrology. If you had to bet, would you put everything you have down on the fact that it's 100% false? I doubt it. There are an enormous number of human theories that live on this gradient between robust concrete evidence and conflicting evidence that when averaged out is a tiny to non-existent measurable effect. Yes, many of them will turn out to be wrong but clearly not all of them.

All that said, at the end of the day I 100% agree it's stupid to apply the golden ratio to art thinking you're learning something about the nature of beauty. Humans are satisfied imperceptively differently through a large range of surrounding ratios, they only really start having preferences at extremes. Artists use it because it's a convenient system to layout a fractal spiral if their art incorporates that. It does look pretty, but so do perfect circles and every other mathematical pattern.