I am also surprised by this. What are you basing it on? For arbitrarily comparable online communities, it looks like emacs.stackexchange.com is twice as active as vi.stackexchange.com
> What are you basing it on? ... it looks like emacs.stackexchange.com is twice as active as vi.stackexchange.com
A couple of things about this. For myself and many others, the reason I started vi in the first place is it's been installed by default on many kinds of machines. On SCO Unix and AIX from my youth, for example, this was the editor you used on a vanilla install of a machine to get things going. So this is part of why the install base is larger.
Another part of why the emacs community is more active is that Vi is just an editor, while emacs is more of a programming language and I daresay nearly an operating system in its own right. Because of the amazing power and flexibility of emacs there's a lot more stuff to discuss for Emacs than Vi.
My computer books convinced me that emacs was the better editor, but it wasn’t installed on the server. vi was. So I learned vi and Perl on my lunch breaks.
Also, if you sum up all the JetBrains products (which you can get as IntelliJ Ultimate if you shell out the money), you land in the vicinity of 63% (not vim-related but a neat fact)