New devs today definitely have to care more about LinkedIn than older devs, most older devs can hop from job to job with referrals from dev friends or something similar. The tech boom and venture capitalist funding of the tech industry is starting to die out, which is making jobs in this industry a lot harder to find. So having something like an incredibly polished LinkedIn and resume can be the thing that make you stand out in the crowd of new devs.

Once you're established you definitely need LinkedIn less. With the job I have now, I have a few friends who could give me referrals and put in a good word for me, but that was not the case at my old job. And before this job I was a junior Dev so my experience wasn't that impressive.