That's what I was thinking. People are far more searchable than they were even 10 years ago, but having only a first name to with the face gives the contestants a little more of a choice to come out into the social media hellworld only if they want to.
I remember watching a late '50s/early '60s game, probably on Jamie's GS Vault, where they had a home viewer contest. The host pulled the card and read the viewer's first name, last name, and address on the air. I literally can't process a time when that would have been okay.