I've definitely seen my coworkers discriminate against interview panel candidates who don't have fleshed out linkedins. They look "sketchy" is what they'll say, one guy routinely compares the dates on the CV against linkedin profile dates and if they don't match flag the person as honesty issues. Also they'll bring up if they don't have enough skill endorsements in core competencies for the roles. I had no skill endorsements so after hearing my coworkers talk about how they check for that I got a few! So aggravating but it happens and people definitely rule out candidates over their lack of visibility on linkedin.