I have yet to see a real performance where this technique is used artistically and in a way that sounds pleasant.
[1]: https://onensemble.bandcamp.com/track/after-rain
[2]: https://onensemble.bandcamp.com/track/yamasong
[3]: https://onensemble.bandcamp.com/track/yamasong-campagna-remi...
The story is great, and the mix with blues is really interesting. The dude has the most thunderous voice I've ever heard. Subwoofer gold.
So I definitely agree that the level one might consider a solo song, with melody and changing chord progression and/or oblique harmony, sung by a single person in solo, is rather rare.