It’s got nothing to do with tradition. It’s the idea that a team could play mediocre to slightly above mediocre baseball for SIX MONTHS and just have a hot couple weeks and get to the World Series because that’s how baseball is. That’s why the 100 loss marlins might take a series from the twins. The teams with the best records in MLB win the World Series less often than the top seeds win the Super Bowl.
Now, with both leagues playing each other and fewer divisional games, you could make an argument that the MLB playoffs make no sense. We try to decide in one month what’s already been shown in 6 months.