Interesting topic as always Doc.
I think this is all subjective. For example, what electric bass for jazz, gospel, rock, etc should sound sound like is going to vary based on everyone's earballs. So just defining the standard in some universally acceptable way is likely not possible.
Me personally, I don't think there is one bass that does everything because I hear different genres differently. But I definitely believe some basses or electronics configurations do more than others.
As to why people go through careers on one instrument, I think that has to do with comfort and familiarity. A virtuoso like Victor Wooten will be that same virtuoso no matter what he plays, but he feels most at home on a Fodera. It's like an athlete finding the perfect pair of shoes.
Just my $.02
When it comes to an artist using one bass, I think there are a few variables. For years, a Fender and flats was the standard sound, so a Chuck Rainey, Max Bennett, Joe Osborne, Jerry Jemmott, were under no pressure to sound different on a gig. Later studio guys, like Marcus Miller, became hot because of a particular sound, in the Eighties, Marcus Miller was slapping his Jazz for everybody and their momma. Louis Johnson was doing the same thing with his Stingray’s and Sabre’s.
Finally, you get someone like Nathan East, who uses super versatile basses and simply seeks to blend at every session, not sonically dominate.
