You added a second variable by throwing in the part about the photographer which should not be in this question. So I'll counter your variable by changing it to: "in the hands of the SAME photographer."

In the hands of the same photographer, taking the same shot, in the same conditions and environment, on the same camera body, or two of the same camera bodies side by side on tripods - yes the considerably more expensive higher line glass will create a much better photo. I spent far too many years using mediocre glass. When I experienced Leica and Carl Zeiss glass, my photographic quality improved in leaps and bounds without me changing anything else at all. If you have a Nikon body, put one of Nikon's high end lenses on it and see for yourself. Same with any other brand. You'd be better off keeping a 10MP body and putting a very expensive lens on it than to use a 18MP body and use a kit lens on it in most cases.

That's not only true of dSLRs either. You can see it happen with P&S cameras as well. A $139 P&S versus at $189 similar model with Leica or Zeiss glass is astoundingly superior.

The widest aperture available is also not the only thing that makes a lens better. It's the glass and design of the elements and how they work together. The f number is just a side effect of those factors.

Comparing this to the music world, I had a saxophone professional jazz player tell me he would rather take a school band level instrument (equal to an entry-level camera body for this example) and put a pro-level mouthpiece and pro-level reed (equal to a high end lens) on it for an important live performance than to use a pro-level instrument (higher level camera body) with a cheap mouthpiece and brand of reed (entry level lens).