Lest it be unclear, I am of the opinion that plagiarism is always wrong. It doesn't matter if someone is doing so for a paper, for a blog, or whatever - if you take someone else's words and/or ideas and copy them, then you better properly hattip or attribute what you have taken. I do not like unsubstantiated claims of plagiarism, or accusations when someone comes up with the same examples that are obvious, etc. As for anonymous blogging... well, it has its problems (and positives) as well. This is just one more reason - as others have noted - not to give too much credence to something you read on a blog, particularly an anonymous one, or to the people behind anonymous blogs.
If you don't know what I'm talking about, you're probably better off.
Have a wonderful Shabbos Chanuka, everybody!