Yeah, if you're going to exclude the common use cases, obviously it's going to be rare. (:

People still use local storage.

(I'd also like native ext4 support in Windows.)

Yeah, but when I boot Windows for gaming, I don't care about sharing data with Linux.

And given the availability of cloud storage, I can just upload whatever little I need to share.

Not all dual boot systems are "main OS" plus "wintendo." Quite a lot of the ones I encounter on personal machines are, certainly, but people doing actual dev stuff on both is still a use case.

Valve is working hard to change that.

Used to dual boot, but with the combo of steam/proton and VFIO passthrough + looking glass, it’s been really solid to just run both at the same time. File sharing between the two is pretty easy in that case, because it’s just the usual rsync/scp tools or SMB share.

Although, I’ve found I very rarely need the guest for gaming anymore, more so for opening the odd Photoshop file and similar tasks.

This is where I am at now.

In 2010, used to dual boot. In 2014 or so, I switched to VFIO GPU/SSD passthrough and never booted to Windows again. In maybe 2019 or so, I pretty much stopped using passthrough even, though this is partly because I stopped playing a few games that proton didn't run (mostly because of e.g. Easy Anti Cheat, etc).

I don't even have my windows ssd installed in my tower any more, that's how little I expect to need it these days.

Virtualisation is really laggy if you have no GPU acceleration, there are ways to get it working but they either need two GPUs or are still slower than native