I'm pretty certain that this interesting article was written to a deadline for the publication and it has been researched along familiar lines - previously published articles and the evidence from recorded music and interviews with those people who for many reasons were singled out as being worthy of interview.
I suspect that this sort of debate could continue ad finitum, but I think the origins must go much further back in time, to before the music was ever recorded and indeed before there was sufficient interest to write about it.
There was no mention for example, of the competition between the guitar players and the piano players of the day to create the sounds of the popular music of the time.
There is also the problem of the precise definition of "Country fingerpicking". If your definition includes a particular finger pattern using a a prescribed number of RH fingers applied to a specific type of music (also subject to a definition!)we could get into all sorts of murky arguments.
Welcome back JP - as usual your threads are of the greatest of interest and here in the UK it's late so I'll let the arguments develop and come back to it when I'm awake!

Dave Bennett