80s
For many, at the beginning of the 80’s the most commercial form of R&B [until the phenomenon known as Thriller] was mainly a continuation of the Disco sound albeit with a few alterations to instrumentation. Most noted in those instrumental changes was the adaptation of even more electronic synthesizers and the rise to prominence of the drum machine. The net effect was the demise of the large self-contained band and more of a focus on a small team or individual for the creative process.
A few legacy acts were able to hold sway until the middle of the decade but by decade’s end there would be a seismic shift in the music as youth culture, a shift that has not swung back sense.