Great question... I think the answer to this is constantly evolving. The way I see it:
50 years ago - > It used to be almost 100% rolodex & good old fashinoned network.
Last 10 years -> 50% rolodex & old fashioned networking - 50% LinkedIn and other networking platforms.
In the next 10 years -> Smarter SaaS solutions that give access to the right people in the right organization through a good use of the large amount of data we have. Check out the responses to this tweet from Ben Tossell (I have no affiliation, but think the responses hold some good gems) https://twitter.com/bentossell/status/1040618395312566276?s=03