I don't agree that it has been driven almost to extinction.
There's still plenty of people doing it and there's nothing wrong with it at all, quite the opposite.
Perhaps it's just fewer and fewer people want to hear it that way.
I sing and play lots of different tunes and songs in the true folk tradition, ie changing words, tunes, tempo, keys etc to suit.
Isn't this a folk tradition or process.
Some of these are new songs and some very very old.
Some old tunes and songs I have reworked probably a dozen times over the years.
Just because someone sung it a particular way in 1925 does not mean that is THE way to sing it forever more.
I wonder what it sounded like before 1925?
Compare some of the real early bluesmen's versions of the same songs. Which one is the traditional or definitive one?