You know how moving files of any size within a single drive is instant? Because (depending on the file system) usually nothing is really moving, the OS just updates the address table for the file system.
I've tried moving a folder of 1000+ files to another folder using Dropbox web app, and it just couldn't do it! "Too many files" my ass!
It's not like the browser is doing the work! Or files have to be downloaded or uploaded. This is just a `mv` command invoked remotely. They suggest I do it on my own computer.
But what happens if I do that? Surely, Dropbox won't upload thousands of files afresh, it WILL move them remotely.