I've seen people use "Bob" other places! Moreso I think right after the term was coined, but there are a few diehards who still use it everywhere. I always got the impression that it was more "this is a story that is not about relationships but has relationships in it" than "this is a story about relationships, but they are ambiguous ones", which tends to be my problem.

Also "Bob" is a term of deep religious significance with me, so I always do a double-take when I see it on fic. :P