The recruiters in this article are hiring for "top law firms, consulting agencies and investment banks." In those jobs, your number one priority is selling to the wealthy and/or powerful, so this sort of selection makes perfect sense. The recruiters are looking for a set of social skills and connections, not hard skills.

This has been going on forever, and there really isn't any way to "fix the problem." People - including the wealthy - are simply more comfortable with others who share a cultural background. Sales jobs have always sought people with preexisting connections to potential clients.