My current job cold contacted me via LinkedIn. I use LI minimally, basically only to establish connections with my network, and it already gave me huge value back.
I could imagine that working.
For most people though I expect they're just one of many and odds of spam / scam contacts greatly outweigh legit communication.
However, one thing I haven't mentioned is that I am based in Europe. My small sample size of people reaching out to me is showing that US contacts are usually less serious (e.g. ghosting). Maybe the US experience is so much worse overall due to this?