[borroka]

There are also incentives for others to include him as a co-author despite the fact that, presumably, he has come nowhere near the minimum work that would be expected to allow him to be included as such.

The question "Did you publish a paper with [famous scientist/researcher]" is not too different from the question "Did you go to dinner with [famous actress/entertainer/]" in other contexts. The give some clout, recognition, some minor envy from others.