It's how I got my last job. I haven't actually been hired off my resume in 10 years. Almost all of my network today do the crap I'm trying to get away from.
OP here. FWIW I got my leads entirely off of spamming my resume around. For the prior 15 years I'd done freelancing for local companies and had a few-year stint in a small company, so didn't have a network. I was in small-town Michigan so once freelancing dried up I knew moving was going to be a requirement. Thus I was able to spam the whole country. That probably helped my cause a bit.
I noticed you mentioned LinkedIn in another thread. FWIW I don't have an account and it didn't appear to hurt me.
I've changed jobs three times since I was 40, but in all cases I knew people at my new employer who could sell me internally.
I don't think it's so much age as it is that employers don't want to take as much risk on an unknown person for more senior level positions.