It's hard to overstate the importance of this. Without networking, your chances of landing the kind of job you _really_ want are vanishingly close to zero. Every single one of my civilian jobs has come about either through personal friendships ("hey bityard, my work is hiring and I'd like to work next to you") or due to name recognition, e.g. moving in and around the same groups of people that the hiring people are in. I have probably blindly fired off less than two dozen resumes in my decades-long career and while some resulted in an interview, none resulted in a hire.
For someone just starting out in their career, maybe blindly firing off 100 or 200 resumes for entry-level positions is the only option they have. But they should also be broadcasting their availability far and wide to friends, family, randos on the street, basically anyone that will listen. Local tech meetups. Online tech meetups. Career fairs, etc.
But if you've been in the industry for more than 2 or 3 years, and don't have a network that you can leverage in a job search, that is something you need to fix like immediately. That well must be filled BEFORE you need to drink from it.