I did not say that plagiarism is the worst, I said one of the worst. What's wrong?
You have serious problems if you think that plagiarism is one of the worst things around. What about rape? murder? fraud?
The matter is, people tend to plagiarise to hit their post quota, due to their laziness hinders them to spend a couple of mins to brainstorm and express their ideas. Simply opening a website, clicking on one artcile, copying part of the article, and pasting that article's paragraph here. They finish their works, less than a minute. And, most of members whom plagiarise don't care about their contents they posted, of course they don't care about any contributions to the forum, instead of stealing free money.
Yes it is bad, even more so if it is done to pass skill tests, but if you are talking about content theft and reposting online is relatively minor. One of the best parts of the internet is sharing information and growing knowledge, frankly it doesn't matter in lots of situations whether a source is quoted or not.