Surely it depend on what constitutes doing “it all”…
Fat bikes have their place, they make most sense for bike packing/Adventure touring or whatever, anything where you spend lots of time lugging loads across Snow, Sand or Swamps, but here in the UK once the novelty of riding one through a muddy winter wears off you’ll just get pissed off riding the thing all Summer, and so would your riding mates, waiting for you to drag your Niche-core monster truck up every hill, waiting for you at the bottom, only for you to tell them how great it is on the Descents…
I’m sure you can use one all year round, but that doesn’t make it a good idea…
All IMO, YMMV, etc of Course…