Because it requires many rare factors to come together. First, you need an absolutely junk center lineup. Not just bad, but as bad as the furiously tanking Toronto team created by essentially pulling random bodies off the street. Second, you need the team in the absolute tanking mode, otherwise their coach would quickly recognize the horrible matchup and try to remedy it by going small etc. For Toronto it was keeping getting abused at the center that gave them a chance to lose the game and the coach ran with it. Such blatant tanking was rare in the past.
Now, on the other side you need a young good center (almost all of the other records on that list came in the very first year of Shaq, Mutombo, Robinson etc. careers) who goes all in. Players like Davis or Jokic could punish horrible mismatches and ran up the score but they would ease up once the game is not in question. They are saving energy and health for long-term, for the playoffs. So, the opposing center should be on the team who is not competing for the playoffs (and is quite bad in general) but REALLY wants to prove himself in this particular game. And that is Kessler, who is in a breakout year and in a contract year, on a team that routinely keeps him out of games when healthy. He is so hungry for ANY opportunity to play and he correctly thought that he was the best player on his team, a difference maker - and he was brining to make difference.
Take it all into account and it is pretty rare. Currently, the only good young center on a bad tanking team in the NBA is only Kessler. Everybody else of note has better things to do than going ham on varsity players.
