You don't have to have a LinkedIn profile to get a job.
That said, having a LinkedIn account and using it can be beneficial in finding a job, in several ways that I suspect most technical individual contributors don't typically use or gain value from.
1) Online rolodex: It's a convenient way to maintain and grow a professional network, and it's a place where most participants actively endeavor to keep their contact information & job information current.
2) Groups: LinkedIn groups are the equivalent of G+ Communities or FB Groups, but with a professional bent. Participating in groups is an excellent way to get noticed by people you want to notice you.
3) Publishing: LinkedIn added a sort of blogging platform last year that lets individuals publish longer form posts. These can be used for whatever purpose you choose: project details, topical thoughts, career learnings, whatever. They're all then associated with your profile.
4) Projects & documents: Most programmers these days have a Github account or similar, where a portfolio is pretty easily visible, but if you're not in that kind of a role it's not always obvious how to present your work. LinkedIn lets you upload documents & video, and lets you associate projects with your job history (as well as letting you tag colleagues so they show up in your projects, too).
5) Recommendations. Endorsements are bollocks, but recommendations can be helpful, especially from previous or current managers. This is still iffy and I doubt many recruiters or hiring managers actually read them, but they fall under the "can't hurt" category, especially since you have to vet and manually approve any recommendations before they appear on your profile.
6) Job applications & recruiter contact. Say you find a job listing, perhaps on LinkedIn or perhaps not. The odds are good that the company also listed it there. The odds seem (in my experience) to be about 50/50 that the job listing on LinkedIn has the recruiter's name & contact info (LinkedIn profile) associated with it. This makes it SOOOOOO much easier to proactively go after jobs that look interesting, and as well to subsequently make direct contact with interviewers & hiring managers.
Take all this with a shaker of salt, because it may not actually be useful for you at all, but it has been extremely helpful for me. I've spent quite a bit of time cultivating my account and working on my profile the past few year and it's reaped benefits. If you're interested, take a look: http://www.linkedin.com/in/elliottally