That's right ralph.
There's nothing wrong with that class name. Also, even though it would work with your descendant selector as well, it appears WebAIM has a lot of content like that one, for accessibility, and as such they used a "hidden" class.
It makes sense to use a class only if there are more accounts to be managed on a page. This is usually not the case, you first log in on a single account and then you manage that one.
You already quoted the CSS in #10. Pay more attention. Go over to the WebAIM page, first.
Here it is, if you missed it:
With a little bit of help from Firebug, Dragonfly, Developer Tool, Inspector, depending on the UA you use, look for the "breadcrumb" id. It's all there. Even the "hidden" class. That span doesn't have a semantic role, being a span and all, it has a structural and presentational role.