I get a few mails every month/week about some potential job that I might qualify for, and most of the time the job content is pretty in tune with what I want to do. So LinkedIn costs me nothing, but does offer me value. I don't see why closing my account would be liberating.
It's a one-sided perspective of achievement as it does not show the failures of a person.
There's a charm in not bragging so much about your achievements and instead admitting we're all imperfect. The people I met that have achieved the most in life hardly bragged about it nor did they have "all-star" LinkedIn profiles.
There's nothing wrong in outlining your achievements and it is quite necessary if you're looking for a job, or if you're a consultant looking for clients, or if your startup died and you're looking for a new adventure and so on.
LinkedIn is first and foremost a repository of online resumes. Resumes are by definition marketing pamphlets.
> The people I met that have achieved the most in life hardly bragged about it
If you pay attention, you'll realize there's a selection bias going on. The successful people you've met, are probably those whose achievements are known by everybody in their field. This is probably why you've met them in the first place.
Like, when I go to a conference and I see somebody I know to be a really good developer based on my interactions with him on mailing lists or his open-source projects or the startups he worked on (or other such criteria), I do want to shake his hand and say hi. I have less such inclinations for people I know nothing about and I suspect my behaviour is not atypical.
However, many people don't have achievements that are known. Many people may have done wonderful stuff and yet nobody will ever know about it, unless they tell their tale. And yet this is precisely what they need to do for growing in their careers, for getting to work on interesting stuff, for getting higher incomes and so on.
I appreciate modesty, but sometimes it's not a virtue. Knowing how to market yourself is a necessity and yet engineers are really, really bad at doing it.