Sad to see so many replies assuming bad intent. GP pretty clearly meant "to the operating system, it works just like a network filesystem". That's an interesting technical detail, not the start of a flamewar.
I think the problem with making this change to more generic networked protocols is several aspects become a lot trickier then you can't impose limitations on the filesystem.
The biggest problem, as usual, is invalidating the local cache. For Dropbox, who own and implement the authority on the shared drive state, it is a _very_ (relatively speaking) simple problem.
Other protocols like SSHFS have to deal with filesystems of all kinds. Many of those do not support anything like inotify, and polling over huge directories would be horrible experience or performance wise (long delay or slowing down the whole host machine).
That was my read too. But Dropbox itself is just 'rsync, but with a better user experience'. In that case the significant improvement of user experience made for a whole new way of operating. The same could be true with this.