If you have a license, you have responsibilities as defined by the regulations involved, regardless of whether the people you interact with know you have those responsibilities or not.
I wonder if this has been tested in court before. If I'm a licensed medical doctor and then I post under a pseudonym online on things medical-related (while not claiming to be a doctor or claiming to know anything about what I'm talking about), would it be possible to be sued for medical malpractice for that advice? That seems questionable.