I suppose you could view it slightly differently as "What is merit". If you define someone's worth solely by the quality and quantity of work they turn out, maybe. The thing is the "who you know" bit often times is a helpful proxy for "soft skills".
As a manager, if one of my team comes up to me and say "Hey, I worked with Joe at Acme, and he worked well with us, turned out high quality code, participated in the scrum, and wrote tight test cases." I'm going to take that interview. Now if Joe was a right asshat, he'd not have gotten the reference.
As a hiring manager, soft skills are important in my team, they reduce friction, and as any engineer knows, friction is wasted energy. Social friction is no different.