This is rapidly becoming one of my pet peeves, right up there with misuse of the word “literally”:
This thing I’m writing right now? This single entry in my blog? This isn’t “a blog”. It’s “an entry” or “a post”.
Sort of like that piece of paper in a book is a page, not a book.
“Writing a blog” is like writing a book, or a novel. Don’t tell me “I wrote a blog yesterday”; you wrote in your blog. Jeff Atwood writes a popular coding blog. A few days ago, he wrote an entry about…
I’m fighting a losing battle, aren’t I? But I really dislike the ambiguity of having “blog” mean “a single thing” or “a collection of that thing”. I have no problem with language growing and changing (after all, the word “blog” didn’t even exist 15 years ago), but I’m firmly against making language messier and more awkward to use and understand. I don’t think the people saying “I wrote a blog yesterday” are adding anything; I think they’re just being sloppy.