When I was a kid, I told my mother all about my day each day after I came home from school. My mother cared, or at least she pretended to. I exchanged ten-page letters, and later five e-mails a day, with camp friends. I'd often wind up copying and pasting large hunks of content in communications, because I had the same news to share with everyone, with the exception of a few personalized lines in reply to their last message, and inquiries about their individual lives.
This is almost the exact content that goes in the blog. It's not vital to anyone's life but mine and my friends. I don't have to worry about content duplication.
I think some of the Blogs Are Bad! folks cherish the thought that a blog is like a little syndicated column, and should have content relevant to the same types of themes that magazines and newspapers have. There are blogs on gaming, politics, computers, medicine, cooking, cars, et cetera... And when ordinary blogs are often little more than very local gossip columns with the occasional nugget of a good piece mixed in, they feel cheated.
Not very much of the content I put in my own blog is relevant to any type of theme. It's whatever's on the top of my head. I've kept a personal paper journal of one sort or another with reasonable regularity since January 16th, 1991. The content has to fit two criteria to make it into my public blog.
First, would I say this aloud in the company of the group of friends I know reads my blog, while sitting in a public coffee shop? I know that co-workers and family members frequent the coffee shop, and it's even odds as to whether one of them will be in while I'm saying any given thing. So while I may treat the entire virtual coffee shop to my impression of the stupid thing somebody said to me last week, complete with sound effects and diagrams on a paper napkin, I may avoid the run-down of the virtues and flaws of the person my baby sister is dating currently, because I know she wouldn't be happy with me talking about that where Dad might overhear.
Second, will I want to re-read this when I go back through the archives of my blog? One of the wildly popular bits of wasted time in the modern blog are the quizzes and "memes", the ones where you find out what cheese you are, if you are or are not a Pretty Pink Princess, who your celebrity date should be based on your name and favorite color, and if you were an operating system or a file type, which one would you be. Five years from now, when I'm trying to remember what I was up to in 2005, will I really care that I was string cheese and my mouth was a broken .jpg? Not really. I probably will care about the doings of the assorted characters in my workplace, and the reminder why I don't work more 60 hour work weeks would probably be timely.