[iainmerrick]

By these metrics (and the ears of 99% of its listeners) it's a more or less generic 80s adult contemporary song.

That’s what the word “pop” is being used for in “the most complex pop song ever”. Rick Beato is giving an example of a literally popular song, one that somebody suggested they perform an impromptu concert because it was in the charts at the time, and which sounds totally mainstream, and yet has a very unusual chord progression.

And I think “music theory” in this context is basically jazz theory, where a song is boiled down to what you’d see in the Real Book - melody line, chords, and a description of the tempo and groove. Unless you’re doing big band, instrumentation is one of the standard small combos, or just whatever musicians you have to hand. Which again is reasonable in the context of “here’s a song we tried to busk in a scratch group, and it turned out to be crazily complicated”.

He’s not claiming it’s Schoenberg or anything!

[tallies]

I agree it's a good anecdote. It clearly still resonates with professional instrumentalists. But popular music has progressed so much since then that 'jazz theory' is unequip to grasp the complexities of modern recorded music. Beato in the video says modern pop music is getting simpler, but he's just using the wrong tools.

[iainmerrick]

I guess he really means "less complex harmonically". You're definitely right that a lot of modern music has features that would be unimaginable or impossible to achieve 40 years ago when this song was written, both through new tech and stylistic innovations. But I think his view is still very defensible if you focus on pop songs, singable vocal-led pieces that you might attempt in karaoke.

There was a long period where jazz influences were very big in popular music -- jazz itself was actually popular! -- so there were a lot of very harmonically interesting pop songs. I agree with him that that seems generally less true nowadays (thinking of big mainstream singer-songwriters like Adele and Ed Sheeran). But I'd be interested to hear of good counterexamples.