Microsoft used to have a Briefcase icon on desktops for offline file syncing. It used to work for those who used it effectively (it was under used of course). But yes, Dropbox went further than anyone else.
Yes, woefully underused. But in those days networked storage was difficult to set up and removable media meant ZIP drives. Today we have The Cloud™, aka PFM that just works.
Months later, everything in there just... disappeared. Gone one day. For reasons that still aren't entirely clear to me. Never (mis)used it again, haha.
Aaaaand this is why non-tech people are terrified that their computers will bite them.