Of course, this, in the rare cases it is applicable. In my current course we have 400 students with 3 Prof. ... So it is not really applicable.

Another thing to note is that undergrades' first job usually depends on having good grades. Some people will get lower grades and those will complain to the point of suing the university into having a more seemingly fair and unbiased process. (Note actually fair, but I'm pretty sure whoever will get a low grade on the Socrates style conversation will be pissed and demand something else. This kind of mentoring only makes sense in the PhD level really, where grades matter less)