It's not really true at all and I think there's even more than I have found or remember
Edgar took it from Penn in an arguable robbery,
then Benson took it from him in a close fight.
Forrest took it from Rampage in a close fight too.
Pettis despite the big Kick in their first fight took the belt on one move that edged out a round.
Thomson took Melendez title in a close fight by UD,
Mike Easton took Chase Beebee's UWC Bantamweight Championship; Sherdog2009 Robbery of the Year,
Luke Rockhold took Jacare Souza;s title in Strikeforce in a close fight.
Others you guys can think of?