1) The mention of Nikon is to talk about having the choice of shooting mRAW (smaller file) or full size RAW to get approx 46MP files with insane performance capabilities. Our Fuji 24MP sensor and bodies is not at the same level to the D850. That was my point in comparison. The average photographer would be thrilled to have the resolution of a full frame nikon sensor while having incredible AF in low light, tracking capabilities and extremely clean high iso images not to mention Eshutter!!
2) I don't think you've ever analyzed this real situation. Great care must be taken to analyze appropriate aperture to assure no one is blurry in a group shot. So if per say your a Micro 4/3 shooter you can have a wider aperture (less flash power required too) getting plenty of dof to cover a group shot. The MF system you'll need to tighten the aperture a lot more to obtain similar dof for the exact same group shot.
3) Yes I agree many photographers can be pleased with the beautiful fuji crop sensor files vs full frame. Take a gander at Fred Miranda and you'll will discover sensor size is not the only reasons for system selection. There are Fuji photogs loving their system but you can see the differentiation of photogs specifically using their primary mirrored full frame systems for low light AF accuracy, better high iso performance than aps-c for hired events. For some having a clean 12800 ISO, good usable 25600 ISO file is effortless with a mirrored system like the D810/D850, 1DXmk2/5dmk4 so it's difficult to say there is little difference between aps-c to full frame. I appreciate this capability...... MF systems are in a different level of photography. Seems like the photographers know exactly what they need to do with that system. Very specific application focused in their art/work with little to no discussion of the cost of their gear or bragging rights. Leica shooters are some what of a niche category too. They appreciate the extremely unique render and the luxury of raw pure photographic tools. Blanket statement warning LOL : The average photographer will use whatever tools seems fit in their budget. The average photographer probably will not be buying a Fujifilm GFX or latest Leica camera system. A professional (or fortunate $$ hobbyist) with specific needs to their photography will seek niche gear. I'm just the group where I use FF and crop sensor in my tool kit. I will always be a mirrored body user and mirrorless shooter. Different tools for different needs for my personal preference. I just see a lot of talk regarding the Fuji MF camera but if you analyze a high percentage of photos from Nikon/Canon/Sony/Fuji forums etc alot of the photos do not require a Medium format 12-15K minimal/basic system for the average shooter. I really admire the hardcore users requiring that kind of system. A high percentage of dedicated full time pro's sacrifice a lot already with extremely competitive tough market and would stretch or kill their equipment budget for a MF system. Many probably would like to have but not need to have as I mentioned before..... When I think of fuji aps-c bodies I think fun and enjoyable experience. Also knowing your gears limitations when your shooting hired events. BUT when I think of Fujifilm GFX I think serious IQ demands and meeting deadlines for serious work. That's perhaps narrow minded but just my mindset ...... No big deal.....use the tools that you have and maximize what you can do with it. No stress...shoot and have fun!
1) Again though, what does Nikon's D850 have at all to do with the conversation about a Fuji GFX?
2) I've never analyzed this real situation? What does that even mean? I've shot plenty of group shots, I'm aware of how DOF, aperture, ISO and flash balance come into play. When did I suggest what you just pointed out to not be true? Did you even read what I wrote? I'm beginning to think not since you pretty much ignored my main point... it's no different when comparing how you would approach a group shot with an APS-C camera vs a FF camera.
3) I had an a7S for over a year... it's pretty much still the king of high ISO shooting... I really don't miss it's low light capabilities, and that was my biggest hangup on letting it go (not hard to dig back and find me fretting about it). The reality is that the vast majority of most shots are done below ISO6400 for most people, even in events like wedding receptions. Couple in Fuji's faster glass and this becomes even less of an issue. I had a few shots with my a7S that were useable even above ISO100k, truly awesome... but the reality is that it was such a rare need that it's just a non-point as far as I'm concerned. Kind of like how I've owned cars which were capable of 165mph... cool, but doesn't mean jack in the real world and I never took it much above 100. Be honest with yourself, how often do you need to shoot over ISO12800?
In shots at or below 6400ISO the difference was miniscule to my eyes, again, not worth fretting over.
Your final points about niche gear don't really make sense to me either... what's your point? Who in here has argued that the GFX isn't a niche camera? Your point about "a high percentage of photos... do not require a Medium format 12-15k"... again, the same exact logic can (and should) be applied to the argument of APS-C vs FF.
I do agree with your closing sentence though; It's not a big deal and we shouldn't stress and we should all go out and have fun shooting... but I enjoy these types of conversations