Can I offer a thought? (Nicely put, by the way, Al)

Those of us weaned on traditional, light, church etc. music - and, indeed, 50s-80s pop - tend to have chord progressions in our dna to the extent that songs made without them sound 'wrong.'

But there are lots of other musical structres in the world, and one that's gradually come to prominence in the Global North, starting in progressive rock and then moving into 80s+ pop via people like Radiohead, Coldplay and many others is more pattern-based (I would say riff-based but this is more stripped out), rather than chord based. You do get a lot of repetition, but it tends to be skeletal rather themic. Another descriptor is extensive use of seemingly random accidentals - which you soon get used to if you listen to if often enough (as I do on long car journeys with my son).

Music is all about recognition. We tend to prefer music that's quite like stuff we already know, so if you don't listen to a lot of that second genre (as most folkies probably don't) then it does indeed sound both boneless and boney, (if you know what I mean) - or even 'frothy.'

There are, however, millions of (largely younger) people who are well used to those shapes - and to them the Mums are a refreshing new sound in a well-established genre.

Tom

And I'll say again, because it needs saying every day till people stop and think about it: No, I personally wouldn't call that music folk (folk-ish, perhaps), but I'm in a minority. A huge majority of (largely younger) people do think that's the correct word, and have done so for generations - which is why the media (who may have started it in the 60s but now merely reflect popular language) continue to do so. That said, I'd be disappointed if the Mums started winning 'Folk' awards, but only because they obviously don't need to.