Whereas a VM backup means you can rehabilitate a functioning computer for the author with all of their data and __all__ of their esoteric configuration nuances in a matter of minutes. They can effectively have their computer reappear in front of them using any commodity hardware available off-the-shelf from any large town in Western civilisation—no need to rummage around your local community to track down esoteric, period-correct hardware components.
I don't think cloud backups are strictly necessary but given the size of a DOS virtual machine in its entirty, why the hell not? What are we talking about here, one or two megabytes after compression? That's less than one JPEG from a smartphone.
> I drive a car made in 1980
Don't crash.