It is a design conflict.
If they followed real life, few teams would be involved in the later stages of the playoffs. IRL, once a team is eliminated from the playoffs, their fans focus on other things, like baseball. Most basketball fans don't know whether the Lakers or Spurs won the NBA championship this year.
But in a game like BB, this could be disastrous. If someone goes a week or two without participating, they get out of the habit. They might skip a week during the season, and suddenly realize it was actually two weeks.
Originally, BB didn't have any arranged scrimmages. This meant that 5th and 8th place teams would go 3 weeks with only one game per week. This was considered especially unfair since the 6th and 7th place teams might get 3 games, and often with no risk of relegation. The Saturday scrimmage partially makes up for this, and for most team makes an identifiable off-season, without having owners getting out of the habit of logging in.
Currently the 6 non-finalists only miss one game. It would probably be fairer to switch the relegation playoffs to a single game. This would mean that 4 of the bottom 8 would miss a single game, and 4 would miss two games, but always have two games per week.