Industry killed that with production credits, rappers killed it with infighting and money grabs outside the group or money grabs in the group for more money leading to group tension, labels sniffed this out and literally capitalized. Hip-hop started blowin' up and the best rapper out the group goin' solo was the business plan for hip-hop goin' into the millennium like the labels perfected the formula with R&B and funk groups before rappers.
Not only the best rappers out of the group make more money goin' solo, it's cheaper for record labels can push one artist instead of several in a group.
Busta Rhymes' career a good example of this.