I think Vim is more popular with sysadmins because, historically, you could count on Vi or Vim being available on just about any server you had to do some work on, while Emacs might not be. That's still probably somewhat true, although in the world of clouds, containers, and source-controlled, reproducible configuration, it's probably less common to edit files in place on a server.

However, with Emacs tramp, you can edit files just about anywhere you can access, by any means, even if there is no editor installed there at all, using your local Emacs, with all your accustomed configuration. Like popping open a file inside a container running on a remote server by ssh, something I've done a lot of lately, debugging services running on AWS ECS.