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 models had neither buffering nor handshake capabilities. As a result, there would be no place to store received characters while the printhead was moving back to the left margin, and no means for the sender to temporarily cease transmitting characters.