I don't think so. It would have to be very far back or else it would be too easy to make. If it was an easy shot to make, like just behind the 3 point line, then games would just be higher scoring. It would mean that players would score more points and would break all the previous scoring records. If it was behind the half court line like you said, players would just be taking crazy shots to score five points. Especially in high school and younger, kids would take those shots without realizing they're almost never going to make it. In the NBA, the only time it would happen would be in buzzer beaters.