I asked WhatsApp's FAQ;
"If my username corresponds with my real name, it is possible for someone to guess it and initiate a phone call to me (not a chat, but a phone call)?"
It responded:
"Yes, it is possible. A username allows someone to find you and start a chat without your phone number. Once a chat is initiated, the person can use the call button within that chat to start a voice or video call. If your username is easy to guess because it matches your real name, someone could potentially find you and initiate a call this way."
So, maybe best not to use your real name or its obvious variant.
It seems to me that, otherwise, the scam potential moves from information-free random phone numbers to a chunk of information that might reasonably be supposed to have some meaning for the person to be spammed, making credible scamming more likely, not less.