I'm also one of those people who jumps between companies every 1-2 years (not as a contractor but actual employee) and it's meant about a 15% increase in salary

I'm also one of those people who jumps between companies every 1-2 years (not as a contractor but actual employee) and it's meant about a 15% increase in salary every year, vs 4% that my ex-colleagues usually get for their "loyalty". I do very actively maintain my linkedin page, but honestly I got all of my jobs by personally reaching out to companies where I want to work (through their own website). As such, I wonder if this is correlation vs causation: people are really eager to advance their career might want to keep all options open, including linkedin, regardless of whether it has actually helped them in their career so far.