I have been using LinkedIn for 18 years... To be honest, the biggest use of LinkedIn is to conduct background checks on overseas contacts (LinkedIn is blocked in China, so it is mainly used by Chinese who work abroad): what companies and positions one has worked in the past, what position one currently holds, and what business one is responsible for.
Scammers with unclear origins either do not have a LinkedIn account or have a LinkedIn account without any followers.
A legitimate professional's LinkedIn account will definitely have many interactions with professional connections: alumni from the same school, former colleagues, current colleagues, clients, etc.
However, that's all there is to it; I have never secured a job opportunity or client order through LinkedIn.
It would be great if LinkedIn could be made into a blockchain app, so it wouldn't be afraid of any country's firewall. A verifiable entry point on the blockchain is very much needed for checking people and their professional backgrounds.