The purpose of multi account is this one mentioned by you and people often do that in reputation section (sometimes get harassed for posting from newbie account too). But multi account allowed feature is mostly used by the signature campaign abuser. Most of the high profile have another face behind too, as long as they are not caught, they will pretend to have only one account.
However, not everyone is like that. For example, LoyceV created two accounts for two device, same by timelord too. My opinion is as long as you are not cheating, abusing, you are good to go with more than one account.