I understand what you are saying. Getting low is more a defensive thing though. DL are taught to fire low off the ball to drive back the OL. The OL don't want to let the DL get to their body though so that's where the long arms come into play. If it's short yardage or goal line straight ahead blocking that's different, you do want the OL to fire off the line low but most blocking isn't pads popping blocking like that. Pass blocking is very much a finesse game where long arms and good footwork matter the most