Empathy deficit

The absence of nonverbal feedback leads to an “empathy deficit,” and this is what sociopaths suffer from.

If someone says something negative in person and makes you cry, he/she will possibly feel uncomfortable. Unless they're psychopaths, your misery will generate an empathic response and lead them to have mercy. If someone tweets something negative and makes you cry, no amount of emojis can transmit the image of a crying person. If there is no social cue to evoke an empathic response, they might continue their negative assault.