Yes, you are correct. BJJ has evolved through times, absorbing whatever would work. True Brazilian Jiu Jitsu is really the principle of closing the distance, controlling your opponent and ending the fight by disabling your opponent by crippling or unconsciousness while not giving your opponent any chance to hurt you. Any technique through which this principle can be applied can and will be used in BJJ for self defense.
Rolls was the first to actively seek cross-training in other grappling arts, but many popular moves were rediscovered and reabsorbed through the times. Two famous examples are the triangle choke, which was not passed on to Carlos and was instead learned from a Judo challenger, and the Ezekiel choke, which was developed by a judoka called Ezequiel to be used against the BJJ guys in the guard, and was subsequently absorbed into Jiu Jitsu.
You can not unlearn something. Every new thing shown is something in the arsenal.