Okay...that really doesn't indicate how it's useful, nor does it indicate how it offers anything over say Google Analytics. Google Analytics, among other site stats packages, has a referring sites report that lists the sites and pages that send traffic to a particular site, which is the only true measure anyone who isn't employed by a search engine has when measuring the effectiveness of an inbound link.
Site stats packages will also show referring links things like Alexa can't show, such as links clicked on from webmail accounts, links from intranets and extranets, and links that are on pages that may not or will not be indexed. If someone wants "details of there posting", that would be the place to start...if a marketing campaign is being performed effectively, then users will visit. The "SEO backlinks" angle is at best white noise.
So...what does Alexa offer that is unique and that provides some additional level of analytical clarity? What makes Alexa special? What makes it useful? This is what you've failed to answer, so what I'm going to do right now is something I don't normally do...I'm going to give you an out. You get a free pass if you want it. All you have to do is say "I don't know what it offers that is useful" or "you're right, Alexa is useless." Or...come up with an intelligent, reasonable, logical argument that shows how Alexa is useful...and that's going to take a whole lot more than a sentence.