Why do bloggers keep falling off?

Does the novelty of blogging wear off so quickly that people aren't keeping up their blogs? I notice that many of the people I have linked to have just let their blogs go. And I am actively unlinking for sure. Are we all such perfectionists that if we can't be the best (or be Scoble, for example), we aren't going to blog at all? Or are we just too impatient, not wanting to wait until our activity results in something.

I don't get it. Starting a blog implies that you are going to, like....blog. Feels like you are breaking a promise if you disappear without an explanation. Or a goodbye. Am I being too sensitive? ; )