I don't understand how people can be so dismissive of LinkedIn purely for its resume function.
For essentially every "knowledge worker" profession with a halfway decent CV, a well kept LinkedIn resume can easily make a difference of $X0,000 in yearly salary, and the initial setup takes one to a few hours. It's one of the best ROI actions many could do for their careers.
How dismissive many engineers are of doing that and the justifications for that are often full of privilege.
I think this statement is highly dependent on market and geography. I, for one, have mostly received scams. For the occassional real contact, we shifted away from LinkedIn as soon as we could after the basic hello.