Idea standing behind this document is to provide a list of generic UUIDs which manufacturers assign to their iBeacons. There are many companies out there which are making iBeacons - some of them are recognizable brands and other are just small local companies. It doesn't matter - what matters here is to have a list of as many brands here as possible.
Imagine simple scenario: You're a developer of a mobile applications and you're not creating an app for a specific company, just a generic application which will be compatible with all iBeacos available to the end user.
With this document you can simply take those manufacturers UUIDs and use them in your app.
Of course, some providers may customize their beacons so they have modified UUIDs but this is the security/privacy thing and if you're developing an app for all iBeacons you probably won't care about them (but if you know any, feel free to enter it in this doc).