Unlike modern printers, these early printers contained essentially no buffering, nor did they do any handshaking, so there would be no place to store the characters which would be received while the printhead was in the process of returning to the left margin, nor any way to tell the sender to temporarily stop transmitting characters.
Unlike contemporary printers, these early printers had no buffering or handshaking capabilities. Therefore, there would be nowhere to store characters received while the printhead was returning to the left margin, and no method to instruct the sender to pause character transmission temporarily.