A vaguely related theme about work songs dying out in the 50's.
https://en.m.wikipedia.org/wiki/Waulking_song

https://www.youtube.com/watch?v=t886nGdlRps&list=PLnOSH5j1sQh-RonDbQ0h7ryDaixFdoqdb&index=9
A very interesting comment right at the end of the clip:
Capercaille recorded a Waulking song thar made it into the top 40

For me this example above makes the point that definitions within the genre need to be fluid.
It is a work song that lasted much longer than shantys.
It is undoubtedly a folk song
Related songs have become pop hits (The "Sky Waulking Song" is from their album Nadurra released in 2000, sung in Gaelic)