It's pointless to compare vim, atom, and eclipse in the same thought process because they're completely different tools for different tasks.
> ... as to why vim is superior
Vim is not superior categorically. If you expect your editor to autocomplete Java code for you and fill in imports and look up methods for you, and have extra features that aren't even connected to editing, Eclipse is tremendously better. But Eclipse is a different tool. It's a full IDE.
Atom is a gui-based editor.
Vim is a cli-based editor.
I've been seeing people left and right comparing editors as if there were some definitive lockdown about to happen that binds you to a single editor. Use whatever you like and what gets your job done. You can also use more than one for more than one task.
I use vim when I'm editing files via ssh remotely, Sublime when I'm editing local files, and VS Pro when I'm working with .NET at work, because these are, respectively, my tools of choice for these tasks.
None are "better" or "worse". They're just different.