Do you have friends? yes you have. Similarly i have many friends, and few of them are doing bounty campaign like me. When we get reward , we need BNB fee to withdraw it so that's why we have to transfer BNB fee. So it's not evidence that proof that account is managed by one person only.
More, Royse777 also sometimes need tron fee to send signature reward. And he ask from participants, someone send him fee . Now fee is transfer , Does it mean Royse777 have multiple accounts? Verily not.
Similarly we have to share fee to withdraw reward.