All cases of rule breaking are considered uniquely and not as a general case with the same outcome, while unintentional plagiarism might not exist on the forum, if a user us caught plagiarizing and gets caught, the details of the case would be considered before such user is banned or when they appeal.
Some members are judged on merits of their contribution to the forum over the years, this could result in a lower ban, with restrictions of signature space possibly,
• If a user makes an error on imputing the site link, this would also be considered by the mods, sometimes using quite tags, or simply "" "", is usually enough to avoid any punishment.