Armed forces are a prime example of this, years of service result to not a lot in the big wide world and there are people on here who will testify to this, and how hard it is to get work.
I totally agree - only for those who joined the wrong trade, don't have/didn't gain professional qualifications during their service. Your career path and education are what helps. Linkedin isn't going to help someone with no real transposable skill set or qualifications. And those who do have the skillset and qualifications will find work easily without linkedin.
And you sir are talking bollox - fact. ( job and skills wise post forces )

I'm not talking nuts.
Perfect example is yourself. You found work, sure, but not everyone will right away find work that they wanted. The above is nuts to say that ex forces people won't find work very easily.
All of the above is complete bollocks, the idea of Linkedin is that you create a network of people verifying that you can do what you say you do rather than waving slips of paper. It adds personality to your CV, a whole host of references from people who wouldn't normally reference and the chance to discuss ideas and get yourself known within certain groups and circles. Linkedin creates a level playing field that allows the man at the bottom and the man at the top go head to head for jobs.
If we took an example of say, a bricklayer, you can have a young lad with level 3 or an old boy with nothing but experience under his belt. From a qualifications point of view, the young lad out performs the old man easily but in terms of testimonials, backing and referencing the young lad wont have a patch on the old boy. But as an employee i'm looking for someone to say... rebuild a specific arch type on a big project, the young lad could have done nothing for 1 year but build arches with project x whilst the old boy hasn't done it for years. The CV's of these two people will not talk about specific projects, simply because you don't on a CV, but the linked-in can give all this extra info allowing the employee to make a much better informed decision and providing both parties equal opportunities in terms of employment.
Comprehended?