If you use LinkedIn, BEWARE Huge flaw found
medium.com
medium.com
I'm not sure how LinkedIn could get that information without having a huge staff of people who verify each new, unique company that shows up in their user base. There are millions of companies in the world, most of them not as well-known as Google or Nike, some of which may not even have a web presence. Even if they're on the web, the domain they use for e-mail may not be the same as the domain of their public web site (I've seen companies with www.xyz.com vs. joe@xyz-corp.com). To add to the confusion, there are completely unrelated companies with very similar names. And companies are born and die every day.
Given the daunting nature of this task, I'm not surprised that LinkedIn doesn't attempt to validate the corporate affiliations of its users.
The unverified adoption of any job title of any company is still a pretty serious issue though.