The use of an IP address rather than even a username is often a clever device that serves a multitude of purposes An established username allows you to look at their other contributions and perhaps discern some clues as to their identity or affiliation On the other hand a relatively new account if the user demonstrates experienceknowledge with Wikipedia can provoke allegations of sockpuppetry If the new user does not demonstrate experienceknowledge with Wikipedia he is pretty much harmless as he will be ineffective in pushing his POV since he cannot game the system through his familiarity with the rules and norms An IP address provides the opportunity to disclaim responsibility for edits since they could have been made by someone else using the same terminal and if the IP address shifts can make it difficult to figure out which edits are being made by whom