That, however, is the exact problem; most blogs are simple rehashes of the same things that have already been said. One could argue that this very article is a prime example of why someone shouldn't have (or rather, doesn't need) a blog. It isn't an attack against the quality of the writing itself, but the reality is that there's little of value because everything there has already been said countless times before.
Depends on the purpose of the blog. I maintain a blog for two reasons. One, writing about problems and their solutions as if I'm explaining them to someone else is a great way to solidify the concepts in one's mind (similar to rubber-duck debugging[1]). Two, having an active blog is a signal to potential employers that you're active in the ecosystem. Even if someone is rehashing the same old topics in their posts, seeing how they think and how well they write can be a useful indicator.
Those are both reasons why it is in your interest to write a blog. They are not reasons why someone might want to actually read your blog (short of prospective employers).
Fiction is read for the fun of reading a different take on the same basic tropes. Most programming blog posts are not read for even remotely similar reasons.
