As I observe acts like Mumford & Sons and the like being hailed as the vanguard of "Alternative Folk" I must take issue...
10 years ago or so I was working with artists like Devendra Banhart, Vetiver, Akron/Family, Larkin Grimm, Feathers, Fern Knight, Fire On Fire and hung around the Philly psych-folk crowd (Espers, Fern Knight, etc.) a bit. Naturally I became familiar with the past musical histories of the performers I worked with and talked musical likes and dislikes at backyard parties and between sets at local shows. What came up on a regular basis was that most of these people had had backgrounds in the avant garde underground, had played in noise-bands, been skronk-rockers, done performance art, purely experimental music, etc; and most of them continued to follow the work being done in those genres. Then tt some point, they'd collided with the aesthetic corpus that Greil Marcus dubbed "Old Wierd America," a prime example being the music Harry Smith had anthologized on "The Anthology of American Folk Music." This was authentic folk music that was noticeably eccentric in lyric content, musical composition and performance - both instrumental and performance -- just the natural outcome of individuals expressing themselves as best they could with resources (educational, cultural, etc.)at their disposal. The work "The Anthology..." documented was singular and the visionary as the best efforts of someone with Guggenheim grant working for years in state of the art studio. This body of work proved highly seductive and influential to artists who might have felt that they'd exhausted the possibilities of amplified post-rock and would consequently begin examining the possibilities of creating avant-music using acoustic, often arcane, antiquarian instrumentation
The results(avant folk, psych folk, freak folk - whatever bin divider tag you prefer), were pretty marvelous. Subtle, low-key, sophisticated, catchy and consistently off-kilter in the most delightful ways. A decade, later most of it holds up fine and in fact continues to sound fresh and prescient -- and out of joint with the current crop of "Alternative Folk" front-runners.
I'd suggest that's because artists like Mumford and Sons are "Alternative" only in terms of being relatively young and marketed to "alternative" consumers (which I assume means anyone who's not a fan of One Direction, Kate Perry et al). They're "folk" only in terms of using acoustic instrumentation. But the grounding in avant-garde/experimental music and in the actual "folk" canon (the repertoire that people like Bob Dylan were inspired by) just isn't there.
So the point...well, if ya dig things like Mumford and Sons, that's all well and good. Music is divertissment first and foremost. If it eases the stress and strain of living, lifts your spirits, etc. that's what it's for and whatever does that for you...all well and good. But pass this stuff off as new and improved, innovative etc...not so much.