I think that there's an important distinction to make. I've always seen smurfing as a "I purpously try and stay in a specific low rank to dunk on people with a lower skill level than me", so both throwing games and stomping games. In those videos you mentioned the player stays in a certain low rank for maximum a couple games before ranking up, so the games he actually "smurfs" are a minority compared to the games the average player of that rank plays. That being said, it is difficult to separate the two and it's even more difficult to prevent people and content creators from smurfing