This begins to feel a little like the Monty Python "But I came in here for an argument" sketch. You already have a medium format system camera, right? Maybe you don't need or want a TL Fuji 6x9 rf. It's ok to simply not want something. One doesn't have to make an argument that it's bad, just that one doesn't want it. It doesn't mean that other people who do want or use it are misguided.
I don't think "rangefinder" needs to be associated with street photography just because many prominent street photographers used the 35mm rf. There are places where a big RF seems not the ideal tool, for ex if I were going to do a lot of studio portraits. On the other hand, there are many stories on Photrio of people who shot weddings in the 70s using a 6x7 Koni-Omega RF. I suspect the Fujica 6x9 RFs were less common in the US back then, compared to the Koni-Omega and Mamiya medium format cameras. All of these were quite expensive professional tools at the time, and people probably did not flit between systems.
Although not any of those RFs, Bill Owens took many of the shots in "Suburbia" with a Brooks Veriwide, which is a 6x9 viewfinder camera with a (slow) 47mm lens. He used a bare bulb flash for the interiors. I think he also used some other camera, perhaps a Pentax 6x7.