I would be interested to hear from someone here who has utilized this method of networking effectively. Over the past year I've met plenty of contacts/got card

I would be interested to hear from someone here who has utilized this method of networking effectively. Over the past year I've met plenty of contacts/got cards etc. I have not felt the need to contact any of the people I've met, so I honestly don't know what it would be like if I did. I don't have any needs/problems that aren't already solved by the people who are in my life now, and if someone was really important I'd put them in my phone contacts, which also, is at about 5% utilization, compared to the total number of people in there, and all those people I at least had some good reason to contact at some point. I think true meaningful networks cannot be built by exchanging a card on a one-off meeting. Am I wrong?