As mentioned by another poster, not in every area or situation (covid...) it's feasible to find jobs without LinkedIn. I kind of agree with you, however I just keep my contact list small. Probably I miss some opportunities with that but at the same time it mostly consists of people who have little interest to traverse my contacts. As soon as there's an equally well working alternative for job hunts, I'm off but I don't see that yet. I'm curious about honeypot.io etc. but I don't like the idea to put people with price tags online