Tim, I think part of the difficulty is a matter of semantics. People have become so accustomed to seeing Google's definition of things that there may be confusion with the cross-over of terminology.
The major difference:
With Google, having been banned is indicated by grey toolbar PR and being out of the index altogether. Being buried (and loss of PR) but still being in the index hasn't been considered being banned, it's thought of as being penalized.
Many, many times over the past few years people have asked what the difference is between having a penalty and being banned from Google, and that's the explanation they're generally given.
So appearing for a URL query but not for keyword queries has, in the mind of many, become a sign of being penalized rather than banned.
That could happen either way, whether it's a ban or a penalty, except in cases where the homepage only becomes a problem - with a penalty or possible technical glitch, or as some have suspected, there's been a filter applied on a select group of keywords - in which case the less desirable, low competition keywords on other site pages will still be bringing in some traffic. If it's only a penalty. With a ban, a site will be toast - out altogether.
I think things will be easier once the terminology reaches a common ground for communication, since individual definitions may vary.