Replace by Fee cannot be disabled in BTC, even if you disable it in your wallet

The addition of RBF in BTC essentially nerfed zero-conf.

RBF allows for transactions to be rebroadcast (and re-spent) with a higher transaction fee in turn invalidating the initial payment. You must wait for one or more confirmations to have any certainty the BTC sent to you is yours.

RBF was introduced to BTC as an option, later an option that was turned on by default, and ultimately became impossible to turn off.

Bitcoin Cash does not have replace-by-fee feature. You can be certain the BCH you receive is yours in an instant.