We’re seeing more blog spam because there are more automated programs for just that purpose coming on to the market.
One way to make a blog less attractive to these programs is to implement the “nofollow” tag if your blog software gives you that option.
The purpose of these comments is the creation of back links in order to improve one’s ranking in Google search results. By using the nofollow tag, you make such links useless for SEO purposes and many of the blog spam programs look for the nofollow tag and skip over those blogs.
Attack and defend is simply part of internet culture.