I would guess extra blood flow could somewhat prevent people from suffering of cold fingers. I couldn’t find evidence for that, though.

Worse, Wikipedia claims it’s easier to commit suicide by slashing your wrists if you have this artery (https://en.wikipedia.org/wiki/Median_artery), and https://radiopaedia.org/articles/persistent-median-artery-of... says it can be a cause of carpal tunnel syndrome.

I don’t see how either could be an evolutionary advantage.