It's not simply a matter of the rules. It's a matter of common sense. If all you did was link to those articles, or if you had credited the source somewhere in your post, then it wouldn't have been a big issue. However, you copied the article without crediting the source, thereby making it appear as if it was an original content created by yourself. If you have to pass off someone else's words as your own just to make a post on a discussion board where you are not required to post, then your post is meaningless -- ergo, spam. That's just common sense. Without common sense, you'll just keep doing the same thing regardless of what you say. Long story short: buh-bye, baby.