Because it is now possibly through cash app and other means to transfer cash to BTC almost instantly, the price of BTC doesn’t impact your ability to move fiat from place to place, so long as the move happens in a window that allows for that rate to remain the same.

Not the fiat movement is bitcoin’s end goal, fiat movement will be (is becoming) a primary function on its way to adoption, if the rate for the initial exchange to BTC and final exchange to USD could be locked in, for the duration of the transaction bitcoin would be more functional to the masses immediately.