This is my believe, but just remember I have been out of the music scene for 4 decades.
I think taking a back seat is not limiting to guitarist, in general, other instruments and even bands has taken a back seat. Remember bands really made popular by the Beatles, before that, a lot of them are singers, in the 60s to early 70s, the bands became popular, then it died down and back to singers. Musicians have to work more in studios instead of standing in front of the stage. Even live concerts, singers hire different musicians to go on the road, no specific band or anything. There are good Jazz musicians that work for famous singers, then in their off time, play their own kind of music. Dave Grusin's band are mostly those kind of musicians. His drummer in the 80s Carlos Vega was a fantastic drummer, he was on tour with James Taylor....sadly he committed suicide in the 90s.
Not too many bands that are famous, very few that last a long time like the Queens. Well, at least thanks to the Beatles that made a lot of musicians' dreams came true for a few years. It's Beatles that started the combos, then to Cream, Hendrix, Santana, Allman Bro. etal that brought guitar and other instruments to the fore front. but in the mid to late 70s, it really die down and back to singers. I don't know the band scene after the 70s, so I can't say much after the 70s.
After I quit in 1979, I completely change the kind of music I listen, no more Rock and Funk, all Jazz, piano and singing.