There's an adverse selection problem with interviewing, in that people who are good tend to disappear from the labor market and when they do appear on the labor market they get snapped up quickly. New grads don't have this adverse selection effect: there is a very good reason why they don't already have a job. This is why companies invest so much in internships: this will often be the only time to snap up a promising young developer before they start building a career at your competitor.
https://www.joelonsoftware.com/2006/09/06/finding-great-deve...