MJH was from the Delta, but his playing style sounds more like Piedmont than typical Delta blues. Here's an excerpt from a piece by Jas Obrecht that I just found:

Besides ragtime, ballads, and blues, what were Hurt's musical roots? "Who knows?" conjectures Ry Cooder. "Here's a guy from Mississippi who's playing in an un-Mississippi style. It's very linear and melodic. What did he hear? He must have heard geechie music, and maybe he heard stuff that came up from the Piedmont area. Maybe he thought it up by himself."

What exactly is "geechie" music? Does it come from the Geechee people of Sea Island, South Carolina (http://users.aol.com/queenmut/GullGeeCo.html#background)?

Anyway, if MJH just "thought it up himself", it's very curious that he thought up a style that is, to my ears, very similar to Elizabeth Cotten's. It seems more likely that MJH and Libba share some kind of common root -- whether it's ragtime, Piedmont, geechie, or some combination.