By taking the time to explain to the user what they are doing wrong, and how to do it correctly, not only do you stand to solve the issue, but you also may learn why the issue occurred in the first place. Maybe they couldn't find the rules, maybe the rules were unclearly written (can't stress this one enough), maybe this user is from another country and your rules aren't translating well through certain services. The reason why some moderators and administrators quickly resort to threats, rather than take the time to properly deal with the issue is because it's time consuming. The reality is, if you don't have the time to deal with each rule breaker properly, your moderator team is too small, and that's the real problem. What's worse is that you've now created a hostile tone for your community which will hurt it in the long run.
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