> I'm wondering why a family of languages should be this dependent on a specific editor...
As mentioned by others, its not. But Emacs is also a Lisp runtime. People who are attracted to Emacs eventually learn some Lisp (Emacs Lisp, closer to CL than Racket et al) or were attracted because of Lisp in the first place. As a result, the overlap between CL devs and Emacs users is naturally higher than that for other editors. This translates into people developing more and better tools for their editor, and higher popularity usually translated into more and better tools (with obvious exceptions).
As mentioned by other commenters, SLIME can be used with Vim too, if that's your thing. But just like SBCL, Emacs is kinda of de-facto editor of choice, not by force, but by love of its users :)
As mentioned by others, its not. But Emacs is also a Lisp runtime. People who are attracted to Emacs eventually learn some Lisp (Emacs Lisp, closer to CL than Racket et al) or were attracted because of Lisp in the first place. As a result, the overlap between CL devs and Emacs users is naturally higher than that for other editors. This translates into people developing more and better tools for their editor, and higher popularity usually translated into more and better tools (with obvious exceptions).
As mentioned by other commenters, SLIME can be used with Vim too, if that's your thing. But just like SBCL, Emacs is kinda of de-facto editor of choice, not by force, but by love of its users :)