All (but not only) people with good people skills and zero productivity would be motivated to say this.
Edit: I think I might have misunderstood what palish meant by "By how fun they are." to exclude productivity and focus entirely on personality. My mistake, if so.
That might be true in the very short term, but in the medium- or long-term, no one actually enjoys working with "fun" people who have zero or negative productivity.
In which case you join me in disagreeing with the statement that 'the only real-world metric that matters is "how much other people want to work with you'."
Okay, fair enough. I shouldn't have taken that sentence out of the original context, which said "By how fun they are." Or maybe I just totally misunderstood palish's point; actually rereading, that seems more likely than not. Apologies.
Edit: I think I might have misunderstood what palish meant by "By how fun they are." to exclude productivity and focus entirely on personality. My mistake, if so.