Its almost true, but it still usefull to use at least 2 XMR wallets, since the first one will be registered in a DB of the service which converted the value from BTC, moving to a second fresh wallet, it ensure that its linked to nothing.if some one can trace 1 xmr wallet then can trace the other i no need for alot of washing the crypto this way will lose lots of money and same result .
just make sure don't use blockchain wallet when using non cleaned crypto