Cause you don't really win with bigs anymore. Last year was an outlier. Literally, it was in a bubble. Even then that had more to do with LeBron and AD being top 5/10ish players in the league.
Its a perimeter dominated league, Unless you have an Embiid or Jokic I don't want my big being ball dominant. I'd rather have a guy who is a top ten defender, cab space the floor, and you don't need to dedicate a big part of the offense to them.