Why Is Pingback Track

Why is pingback / trackback a good design? Why isn't the referer [sic] header the way to automatically track pages that link to you? I was thinking of writing a pingback server for .NET, but on closer look, it seems inelegant. I only had a few hours sleep last night / this morning -- the above is a link to my fuzzy thoughts on the matter. Design reviews requested.

P.S. Happy New Year!