Whence all the LJ spam?

What is up with the LJ spam these days? I got someone posting Harry Potter fan-fic stuff on a Silk Road post. Make that two of them. I got someone with an e-mail address implying they're involved in the term papers for hire business saying something incomprehensible on my "recent changes in LJ" essay. I mean, I delete-and-ban, but I don't get what the purpose is.