Anecdata, but I used to dual boot, until Windows mucked up the Linux boot more than once. Didn't play nice. So I run Windows in a VM now, it's not getting near the boot sector again.

Yep. I have a strict "Dual boot on dual drives" policy now because Windows thinks its too precious.

It only played to their disadvantage, for machines with single storage device now doesn't boot Windows at all or only from VM.

How much of that effect do you think is due to recent Windows versions not playing nicely so you still get some hassle anyway and/or to improving options to run Windows virtually on a Linux host with close to native performance and compatibility?

What do you mean by "not playing nicely". With UEFI boot you can dual boot all day. There is no need to modify MBR. So nothing gets overwritten on updates.

I didn't say dual booting was itself the source of the danger (though it is true that in days gone by that was also a source of problems).

The issue I had in mind was the unrestricted hardware access that Windows has if it is running natively. This is an operating system that has literally pushed updates that inadvertently deleted user data, among other severe problems, and that will deploy its updates automatically to many users. Dual booting won't ensure the integrity of your system against that kind of threat. Running Windows in a virtual environment means it can't damage the rest of your system even if it deploys a seriously broken update without warning. And that kind of virtualisation is getting more practical all the time even if for now it remains the preserve of serious Linux hackers.