Well, I understand your point of view about someone else's code source, I didn't mean to say people are forbidden to look at a correct code and learn from it, but what advantage do you get by simply submitting the source code, if you already know it is already right. There are some people who submit judge's solutions and don't even care about removing the comments the person who did the code made. This kind of atitude should not be tolerated, at least I think it is a really bad practice, you don't have to submit someone else's right code "to make sure it is right".
Learning from other people's code should encouraged, in case you are not capable to have the idea, but not the submission of a code you didn't touch.