It's the price/performance/space/weight relation, which makes it at first a bit silly to go for the FF camera But to go for that one or a D810 still can have some reasons the Fuji can't offer now. Some are upgradeable just by firmware updates (like some menu points which are stupid if you know it can be done differently and better).
Both cameras have their own target groups.
And Toni-A, instead of posting more links of Leica-straps or whatever, you could ask once Wikipedia for "resolution". It is a ratio of how many points to get on the same distance. 300 dots per inch. It is not a comparison of Megapixels because their resolution value can be the same - just one camera doesn't show the same field of view than the one with the smaller or bigger sensor.
Posting something like
"I don't know this guy, however for an APS-C camera, to be able to be compared to a full frame competitor having twice the resolution," is plain wrong and only left remained by BC because it fits well in his reasoning, otherwise he had pulled out his calculator like he did when someone dares to compare different, DoF which never will make it into solid math. Airy discs are hard to measure and soft to compare.
5D IV has 36 mm and 6720 pixel on that distance. 6720 ÷ 36 mm = 186.66 pixel per mm or 4741 ppi (pixel per inch)
Any 24 MP APS-C camera has on 23.6 mm 6000 pixel. 6000 ÷ 23.6 = 254.24 pixel per mm or 6457 ppi
Now decide for yourself which one has the higher resolution. And try to find out the 5D R's resolution
Sony α7R II 35.9 mm, 7974 pixel 7974 ÷ 35.9 mm = 222.11 p/mm
Phase One IQ3 100 MP: 53.7 mm 11608 pixels: 11608 ÷ 53.7 = 216 p/mm
I would never be so stupid to say the Fuji is the best of this choice because her resolution (and all other 24 MP APS-C models as well) is higher than even a super expensive MF. Would be wrong conclusion, but the fact remains, these days standard APS-C have a bloody high resolution.
"I know one thing it's that I know nothing"
Never pretended to possess the knowledge, I posted something I saw asking for discussions/advice
However if you did like the comparo here's a really crazy one:
iphone 7 versus leica M9,