Thanks for the simplest explanation. And bringing back the stones in their proper time (where they get it), it eliminates "Reality B" and "Reality C" and so on. So Steve Rogers created "Reality D", giving credence to the Russo's statement regarding Cap's ending. So that makes traveling time via Quantum Realm "creates new reality" (basing on your explanation). So what's the point of The Ancient One telling, "removing the stones creates dark/branch realities"? So we are dealing now with realities produced by Quantum Realm and removal of Infinity Stone via Time Heist.