Quincy Jones working with session musicians doesn't signify anything about the quality of music that he made or how involved he was in the process in the making of melodies, harmonies and rhythm.
Most people know of Quincy due to his work with Michael Jackson. Quincy's own albums and film scores weren't well received.
The recording process and the building for MJ's albums, Quincy wasn't composing. The harmonies, melodies and rhythms were built by Michael and session musicians and engineers.
It was Michael hanging with Greg Phillinganes, Bruce Swedian and Bill Bottrell. These albums were made in the 70s and 80s, when the industry actually had accurate credits.
This is the problem people have with trying to give credit based on musicianship or technical ability instead of what making an album is actually like. Making an album is about executive decision making, project management and product management. That's what Quincy provided.
Someone like J-Dilla, sitting down with his MPC and mixer, making beats has more input on the musicianship, technical competency of his albums than Quincy Jones producing Off The Wall, Thriller, and Bad.
But people will act like J-Dilla has less musicianship and technical ability than Quincy Jones because J-Dilla doesn't read music and play the fucking trumpet.
Lol.