It all depends on whether the person has anything interesting to say.
I happened across a REALLY lame blog a year or so ago, and posted a link in a thread here. Some Star Trek person. Very boring, nothing to say, no comments in like a year and a half of posts. The person found that link and got wicked upset, clearly, I hurt someone's feelings. I ended up feeling really bad... but at the same time, the blog was so lame and banal, and clearly NO ONE was reading it, it really WAS ridiculous.
At the same time, I came across one the other night from a really smart, articulate stripper, talking about her experiences in the industry. Very interesting to read her perspectives, about that business and other stuff.
You're right, though, not everyone NEEDS to blog. Having the medium available doesn't mean anything if you don't have anything of interest to say.