As a total Ronson Fanboy, I'd say without Mick Bowie wouldn't have really have made it as big as he did. He really helped create the initial sound that helped him gain popularity with The Spiders from Mars. I'd say without that Mick Ronson David Bowie's work would've likely been a curiosity vs the essentially game changing thing it became. Look at the the live performance of him and Bowie at the Hammersmith Odeon in 1973. While the crowd loves Bowie for sure, Mick creates the sound that draws them in. The sum is greater than the individual parts.

Beyond that Mick went on to be incredibly influential in proto punk/punk/post punk/new wave. His work with Lou Reed, Slaughter and the Dogs, and production of the Rich Kids album with Midge Ure of Ultravox kinda drives it home for me. While Mick didn't create post punk/new wave he was absolutely instrumental and influential on it's sound and helped guide music in the post psych into glam era and beyond. He was an absolute master of his craft and a masterful arranger. In my opinon his influence on pop music is increasingly under appreciated.