"ABD" -- what does it really mean?

I thought I knew what the definition of ABD was. It was exactly the same as defined here in Carnegie Mellon's University Doctoral Candidate Policies for All But Dissertation (ABD):

After the completion of all formal degree requirements other than the completion of and approval of the doctoral dissertation and the public final examination, doctoral candidates shall be regarded as All But Dissertation(ABD).

I have, though, occasionally run into the term ABD being used as a somewhat disparaging designation for one who fulfills the formal degree requirements of the Ph.D. but never finishes the dissertation, and then quits the program. Most recently, I saw it in What They Didn't Teach You in Graduate School: 199 Helpful Hints for Success in Your Academic Career, by Paul Gray and David E. Drew.

Number 9 of their helpful hints is one that I strongly agree with: "Remember that a Ph.D. is primarily an indication of survivorship." They go on to say, "You stuck with it until it was done, unlike the ABDs (All But Dissertation), people who complete all the other requirements but bail out before they finish their dissertations."

In hint number 12, in which they remind the reader that "You must have the Ph.D. in hand before you can move up the academic ladder," they say "ABD's may be much abler and more brilliant than you but they didn't possess the stamina (or the circumstances) to finish the degree. In our judgment, being an ABD is the end of the academic line."

My guess is that the authors, as professors, have had to give such stern advice to their own students who were wavering about finishing the dissertation.

My only quibble is with their terminology. What do you think is the correct use of the term "ABD?" Should it refer only to people who have "bailed" on the degree? Or does it refer to those who are in the process of writing the dissertation, having fulfilled all other requirements?