SEO hackers and spammers nowadays are so desperate on getting link juices from other websites. That's why blog comments are common targets by hackers and spammers.
WordPress users comes from various depths of understanding on spam comments on WordPress. Some users does not know that they need third-party or plugins to prevents spams on their comments.
Thus, it is important to have a simple built-in Captcha program in WordPress Comments, which should be enabled from that start. This way spam bots and spam programmers would have a difficulty on submitting the forms for comments.