Trouble with this sort of thing is the subjectivity of 'what chord is this?', taking into account inversions and the like. CMaj7 has C / E / G / B? Who says this isn't Emin6 with the 6th in the bass? It'll depend on the way it's heard and its context within the song, but many approaches can impact this sort of thing.
EDIT: I wrote this without carefully reading the article (oops!). Author does a great job with the "adjustments"...I suspect adjusting to relative minor covers a huge amount of these issues, and the author throws in mixolydian for good measure! There will always be edge cases, secondary dominants, modulations, blah blah blah, but I suspect adjusting to include relative minors handles the vast majority of popular music.
Similarly, I remember McCartney saying he started to realize there was some musical control you could have in a song, not just having to play "root of the chord" bass notes.
"Yeah, as time went on, definitely bass, I started to think, Wow, you know? Once I realized that you didn’t have to just play the root notes. If it was C, F, G, then it was normally C, F, G that I played. But I started to realize that you could be pulling on that G, or just staying on the C when it went into F. And then I took it beyond that..... Once you realized the control you had over the band, as we talked about earlier, you were in control. They can’t go anywhere, man. Ha! Power!"
100%. Every Little Thing She Does by the Police has only two chords in the verses but Stings choice of bass notes make it sound like 8+, root notes be damned.
Playing rootless triads really brings this home. It allows jazz guitar players to have greater better mobility by offloading the bass to the bassist, but if you play a rootless ii-V-I exclusively on the guitar, the chords loose all their color/character.
Great video here talking about the name of one chord in the intro to Stairway To Heaven. Three different youtubers chime in to discuss it. Really shows how much nuance there can be and how ambiguous the naming can be. There was no real consensus. One of the suggestions was "a minor major nine" and another was "e seven flat thirteen over g sharp".
"The name is there to express a feeling. If you don't know any context it can be hard to put a definitive label on a chord." - Paul Davids
That and sometimes chords/notes could be labeled either flat or sharp. I thought that was really an annoying ambiguity until it suddenly made a whole lot more sense--there are 7 letters for a reason; in a given key, we generally want to use all 7 letters to describe the scale tones, instead of repeating one. I think the same goes here, knowing what key the song is in tends to suggest certain chord spellings over others.
I think the difference here is how it functions in the music. Does the chord function as a CMaj7 in relation to the rest of the song, or does it function as an Emin6?
EDIT: I wrote this without carefully reading the article (oops!). Author does a great job with the "adjustments"...I suspect adjusting to relative minor covers a huge amount of these issues, and the author throws in mixolydian for good measure! There will always be edge cases, secondary dominants, modulations, blah blah blah, but I suspect adjusting to include relative minors handles the vast majority of popular music.