Ironically universities have already found a way to defeat that behavior, too: At some places, advisors now also consider a list of students ranked by grades.

Ironically universities have already found a way to defeat that behavior, too: At some places, advisors now also consider a list of students ranked by grades. I have seen advisorship being offered only to the top student in the Professor's class. If you lack ex-ante information how and where your grade rank matters in a year, this just adds a fun new challenge to the first year PhD!