good songs are good songs even without all embellishments/arrangements/production is what they're trying to show.
Someone said once
"Take out all the production, that's how much song you have"
Except the "embellishments" and "arrangements" are actually part of the song and not merely additions. A song is not just a chord progression and the vocal melody. Everything that you hear is literally part of the song, ergo claiming that good songs are only good songs when the backdrop is taken away is the equivalent of claiming that good art must still be good art when you recreate the basics of the painting with a pencil and paper. It's narrow minded and ridiculous. Good songs are good songs for a multitude of reasons, which may or may not include an excellent vocal melody/lyrics, although they may contribute to some extent.
Also, by that logic, everything that does not follow a melody-driven pop structure is not a good song. What about hardcore music? Some subgenres of punk? Ambient music without a lot going on vocally? Instrumental music in general? Music with layered instruments where one cannot possibly take on a substantial role in a "stripped down" version? The list is endless. Are these all excluded from the category of "good music" by default?