Was "mainstream music" originally determined / defined by Billboard charts and sales? Were musical artists who were considered mainstream simply those that reached a certain level of visibility, popularity, sales, chart position, radio air play, or a combination thereof?
That's a sincere question.
If that's the case, that would have meant that music of any genre could enter the realm of mainstream, and even though we might have revelled in learning of a band before it reached the "mainstream", that fame, fortune, or popularity would not cause a fan to turn away, because going "mainstream" was not a dirty word, although it hurts a little when a band leaves its under-appreciated or lesser known status behind.
The more prominent / common and everyday use of the word mainstream now (as it pertains to music) has more to do with connotation, and that connotation is, of course, negative. Very, very negative. It's as though mainstream music has become a genre, because once those words are slapped onto an artist, they are irreversibly classified as over-played garbage. If an artist is a mainstream artist, it's synonymous with:
"The worst music out there."
"Commercialized, conformist music for people who don't have a clue about real music."
"Mainstream music is at its apex of garbage."
"Low quality crap (music)."
According to the original definition (if that was the case), many of the high quality, front-runner artists that many of us know and love, went mainstream. Aren't the Rolling Stones mainstream? Pearl Jam (even though an alt band originally)? Bob Dylan? Tom Petty? Led Zepp? The list goes on. In their day, and into the present day, why aren't these artists called mainstream? Are they or not? Yet ...
It's because the definition and connotation only includes the likes of Justin Bieber, Katy Perry, Taylor Swift, and the list goes on and on, to denote "the worst, commercialized music out there" , so is this fair? And is it a qualifier?
If mainstream music is simply "popular music" then why has the connotation turned into something so unseemly? Any thoughts as to the severity of the downer now defined as mainstream music?