"But to believe that you can always get great results out of a great lighting and subject situation by having only a clunky old camera and one 50mm lens to capture it is not going to work either."
Well sounds like you'd be in Henri Cartier Bresson's shoes then

"So maybe the right approach is that you need better equipment if and only when you feel there are technical limitations to the equipment you presently have and you feel you could be doing more by going to the next level."
Exactly.