I think it's a perpetually increasing scenario that this happens for these reasons:
a) It's a trickle down business. If mainstream sucks with talentless McArtists and McBands long enough which IMO it has for a while now, eventually it crushes the dreams of indy groups and they either adopt a more mainstream sound and get lost in the flow of junk, or go so obscure that they have little following and cannot afford to eat and keep making the same music forever.
b) Group Think or opposite / Singular Vision: Nowadays technology has given way to just 1 or 2 people being capable of writing music easily for an entire group of 4 or more musicians. Artists and players are seeing productions points and writing points distributed via ASCAP and BMI more unevenly because more and more "hired guns" are taking the place of drummers and bass players who were once part of the writing process and thus paid better. The a singular vision of 1 writer is all the whole band derives from in many cases. When there are groups that collectively write, there will always be a few "stronger" personalities in the group that sway the thinking of the masses. If the whole unit is collectively dependent on each other, and just 1 person cannot do it or goes stale, the whole group starts to suffer from the writing perspective and thus begins to fail. It's also like the telephone game, the more crucial people involved to "transmit" the message or sound the band is trying to convey, the more chances for 1 point-to-point failure to happen exists.
c) Touring and merch are paying most indy groups bills. Unless you sell into the McBand / McArtist thinking (most risky approach, but biggest payout), EP, LP, and singles sales won't make enough to keep everyone eating comfortably. Major labels took a hard hit over the last 15 years and had to rethink their entire existence. Well now Indy labels are feeling similar pains. Economy isn't exactly on point either.
d) Technology in general has both helped and hindered many aspects of the business
e) God paid well, finally want a break: Imagine if you spent 5-20 years busting your ass playing shit-holes getting stiffed by bar owners, van breaking down, drugs, partying and finally you make a name for your self, get recognized and make it! It's almost like working 20 years of a 9-5 job in half the amount of time. Unfortunately, that break period tends to sooth the soul. And restless souls make the best shit.
