Take a look at the movie "The Wrecking Crew". It's about studio musicians who took raw material from the record labels' "artists" and turned it into slick, professional work.
If you're familiar at all with 1960's music, you'll recognize their work, it permeates popular music.
The artists themselves were often poor musicians and could not play their own music very well.
After watching the movie, I certainly concluded that the record label added a LOT of value.
Yeah it was amusing to learn how many of the bands whose records they recorded couldn't actually play all the music that got recorded when they toured. Even so, that music seems quite specific to that time and place. It's not as though there weren't any talented musicians in Southern California in the 1960s. It's just that many of the most talented musicians were still playing old-fashioned music, so in the interests of selling more records A&R execs decided to sign less virtuosic musicians and help them out.
So, in that case the record label was "adding value" but the Monkees or the Byrds or whoever didn't really receive that value. They didn't get paid much anyway, so they would have rather made less-polished records that were more authentically their own.
I don't know about the Byrds, but the Monkees weren't even musicians. (Well, one of them was.) They eventually did learn how to play. I bought their "authentic" CD, "Headquarters", and it is, to put it mildly, devoid of any interesting music.
The best thing that ever happened to the Monkees was to have Hollywood write and perform the songs for them, while they lipsynced, clowned around and looked good. The best songwriters in the business wrote their songs. How lucky could they get?
The Monkees were not ripped off in any way. The value they received was becoming famous, and that has enormous value they can use to make money off of anytime they please (and they have done so).
If you're familiar at all with 1960's music, you'll recognize their work, it permeates popular music.
The artists themselves were often poor musicians and could not play their own music very well.
After watching the movie, I certainly concluded that the record label added a LOT of value.