To be fair, Banting tried to get the Nobel committee to award the prize to Best, and when they didn’t, gave Best half the cash awarded.
There’s also the famous story of Jocelyn Bell Burnell, whose thesis advisor got a Nobel prize for her discovery. Though from what little I know, it seems like the Nobel committee deserves more blame than the advisor.
Realistically, unless she is looking for a very prestigious post-doc or has no other publications this might hurt her her too much. If a potential post-doc adviser is looking for a rich publication history, or if she is applying for very competitive post-doc grants it might be a problem. However, for finding a faculty position and getting tenure her publications during her post-doc and then as a faculty member will matter much more. Of course, this is a generalization and the details will be very sub-field specific.
This might not work in her circumstances, but in general I’d strongly advise all grad students to write their own papers, and get feedback from their advisors. That way you work at your own pace and more importantly get the practice of writing, which is going to be crucial if you are going into academia. I don’t know about her field, but my daughter seems to think that publications are crucial in getting a good Psychology job.
My third paper (and first good one) was something my advisor suggested we work together on after Christmas break. I just wrote it over the holidays, and got some great practice and a lot of cred.
The practice also makes the dissertation go much faster - plus you can find out little things your advisor feels strongly about, and avoid them.