...maybe part of the problem is that you can buy one for $25 U.S. dollars. It's been a while since I've seen a $25 piano...
I was about ready to agree with the idea that the guitar is less suited than the piano to playing rhythm and melody simultaneously until Art assiduously reminded me of the thumbpickers (how quickly one forgets..apologies to my Dad, who impressed upon me constantly that Chet Atkins rules)...
Saw a concert recently that featured a couple of musicians, Steve Rector and Eddie Pennington, who are continuing the "Muhlenberg County" thumbpicking style. These guys made mention of a lesser known but accomplished picker, Mose Rager, as a major influence in their musical careers, as well as being the mentor of Merle Travis.
Neil
Then there's Ike Everly