I'd highly advise checking with your referral seller if the referrals they are selling are client or clientless leveling. Client leveling is slower, but has much lower ban rates than clientless.
I've been selling clientless referrals now for over a year with no bans on record. I'm about 99.9% sure the person who spread this rumor said that to deter people from using clientless bots as they're far more efficient.
I bought one of those smurfs and got banned for like 5 level 5 refs or something -.-, but on the other hand my main has 50 level 10 refs and it hasn't gotten banned..