What you're saying is definitely true for the more mature companies (say, 1000+ employees).

I curious if the author has experience with this working for startups and their ilk, which may not have become large enough to have a proper recruiting division.

The challenge networking potentially solves is getting a recruiter to pay attention to your resume, but from that point on your resume has to be impressive looking enough to get you to the interview room. And unfortunately I know (and helped) a lot of engineers who've done impressive work but didn't know how to put that on paper effectively.

That part takes a whole other skill