Take this example: all SO user accounts of user known as "icepax".
I can imagine of any human reasons to create a new user account at SO, e.g. willing to restart with a clean (reputation) history. But particular this one is extreme. The user known as "icepax" currently already has 10 accounts, each involved in only one question/answer.
How and why would one do that? There is certainly more at matter here. Shouldn't it be our task to merge the accounts and inform the user in question about how to use SO and the OpenID properly?