i have a theory on how the monetary landscape of the contemporary music industry is becoming more like other facets of our society with a monopoly emerging.
where only a small % of acts have all of the market share and everybody else is basically dead in the water.
i would project that there are probably <10 major mainstream acts nowadays in america and these <10 acts probably account for more than 80% of all records sold in a year.
a la the vanishing middle class, 99%, etc.
but in music industry terms it's like the college radio-ification of everybody not in that <10 elite "plutonomy".

most of the music that gets a lot of praise on "indie" blogs isn't "challenging" or "iconoclastic" at it's core.
it's just unpublicized pop. music.
that is unless you are one of these people who swallowed the pill that the internet was "leveling the playing field" despite the embarrassing yields it's acts produce on soundscan/venue gates.

something like lykke li's "little bit" would have been a moderately successful top 40 record in 1997.
something like camera obscura's "lloyd, im ready to be heartbroken" would have been a moderately successful top 10 international record in 1995-2000.
i'm cherry picking the best examples, but the same goes for all these records.
azaelia bank's "212" is a top 40 record without coverage.
white denim's "street joy" could have easily been a pop. rock record by mid-late 90's standards.
95% of these so-called indie/underground/alternative acts are undeniably pop. imo.
i guess it's not just rap that has had it's influence via mainstream exposure whittled down to only a few controllable acts.
things are just rough all over.