just to pursue
this a bit, since it's gone beyond 50 posts and clenched up
reasons for the hardening of niche boundaries:
i. niche-media -- i wz reading a copy of FOLK ROOTS over someone's shoulder on the bus last night, it wz my bugbear 20 years ago when i wz writin abt african pop and sent a shiver of dislike thru me yesterday also... the attention and aprpoval paid artists successful in a niche means (i) they don't have do any work to be paid attention by the "centre"; (ii) the centre can hive off any attention it wants to pay to them -- in other words the success of THE VIBE actually diminishes the likelihood of ROLLING STONE needing to write well about the vibe's target subject (and any interraction) [this can be expanded to niche-business as a policing mechanism, i think, the niche-media as the platform for the niche-market]
ii. relative availability for comparison -- in the 60s, the only ppl who knew how the brit blues boom players sounded in comparison to their sources were the players themselves, which allowed them a scope to develop and change and explore, and make something strong (on its own terms) out of something maybe quite clumsy and bad (on the terms of the stuff it was copying) -- ppl who heard it didn't think "crossover", they responded to merely the phenom itself, not the phenon in relation to its source, and the phenom evolved in response to this (naive, uninformed) enthusiasm, far enough to become a thing in itself... today the source is a download away, you don't need a copy to avail yrself of it and will judge the copy accordingly
iii. the language of "appropriation" and cultural ownership -- this is an understandable response to the depradation of the "quasi-imperialist centre", but it's not, in the long run, a strategically intelligent one (vanguards should want to seize the centre, or to operate from it, not to creep off into their own safge no-go zone)
iv. even so the "centre" is simultaneously ruinously contested and not believed in -- not believed in as a civic value in itself, let alone as an untainted possibility
v. practicaly speaking, platforms-as-centres have dissolved -- newspapers, pop mags, whatever, all hive off their various functions into specialist sections so large that you don't have to negotiate "other material" to reach them -- the physical collage-juxtaposition of newspaper layout (which is a basic structural element in modernism-as-a-new-mode-of-thought), complete with impulse to cut, to crisp up, to shorten, is disappearing as the infinite space of the net beckons
[ok that's my starter for 5]