Well, probably. I mean, the point is not that people from other sites that I participate in won’t recognize me; the idea is that it makes it more difficult to google me and trace the sites I participate in, and other potentially personal info alongside with it.
If in Bunpro you happen to run into a user named Ag0g9poLp you could rightfully suspect it is actually me; that doesn’t really bother me since you already knew I’m studying japanese. You haven’t really learned anything new about me, and it is not that strange that we ran into each other in sites related to the same topics.
On the other hand, if you google Ag0g9poLp or 2OC3aOdKgwSGlxfz4jx9 you will most likely come back empty handed.