What is this the noob scarlet letter? If an imposter can make an identical account name that wouldn't make much sense.. Being a 'Newbie' here is like being a Pledge without the alcohol
It only serves as a notice like owlcatz said.
Using a newbie account is more possible to elaborate a great paradigm/scheme in which could involve a larger scale of scamming someone.
(this is an imposter) is only a warning sign that a newbie account could be someone you knew and pull a mischievous stunt.