They have to play a lot of games to separate the good teams from the bad teams. It is fairly frequent that the worst teams can beat the best teams in a one off game or even a three game series, as you can’t control baseball games the way you can a football game and more is left to small margins and chance. However, if you play enough games, the difference in quality will become apparent. The best teams will typically win 100+ games, and the worst teams will typically lose a similar amount.
162 might be excessive, I don’t personally think so, but any significant reduction in games played would significantly increase the amount of chance involved in determining who gets to go to the play offs.