What is the likely origin of professional newbies here in forum;
Is it Origin 1? (May already be knowledgeable prior to joining forum)
Is it Origin 2? (Probability of being an account owned by a user who is already a member here)
Is it Origin 3? ( The- I too know habit)
It is quite possible that someone has been around long enough to change accounts if they wanted to. But, why would it matter? They are not breaking any forum rules.
Nevertheless, as some have already stated, I also believe that most "professional newbies" have some prior experience and basic etiquette of communicating online. There are people who literally know nothing about cryptocurrency and yet post quality content on bitcointalk. For example, some members may be experts in some other fields, not necessarily closely related to crypto and blockchain. So I don't believe they are all alt accounts.