Any music theorist would tell you there’s no such thing as “legitimate song structure”. Verse/chorus/bridge is at most _common_ (though in no way legitimizing) at a very specific time in a very specific culture, there are plenty of counterexamples from the last 50 years.
If you’re interested in stuff like this, YouTube has approachable music theorists making good content. 12Tone is quite good.
I'm sure that's true, but I specifically referred to Western music found on music charts. Obviously I knew the assertion is wide open for attack on the "legitimacy" idea, but I think an objective analysis of hit-song structure would reveal trends that support the idea of optimal "catchiness."
If you’re interested in stuff like this, YouTube has approachable music theorists making good content. 12Tone is quite good.